…Provides LdapRealm Functionality similar to Apache Knox

### What is this PR for?
ZEPPELIN-1472 - Create new LdapRealm based on Apache Knox LdapRealm: Provides LdapRealm Functionality similar to what Apache Knox provides. This is critical as in large enterprise environments Active Directory Global Catalogs are used for lookup with samAccountName and using a DN Template is not an option as their are multiple OUs. Also searching on "userPrincipalName" is risky in an AD environment since the explicit UPN vs Implicit UPN can be different this is definitely the case with environments using Office 365. And the LDAP userPrincipalName attribute is the explicit UPN which can be defined by the directory administrator to any value and it can be duplicated. SamAccountName is unique per domain and Microsoft states best practice is to not allow duplicate samAccountName's across the forest.

In addition to the above changes I have adjusted and moved the LdapGroupRealm and ActiveDirectoryGroupRealm into the org.apache.zeppelin.realm package structure to make all Realm's consistent.

The LdapRealm class also works with role to group mapping for usage within Zeppelin for notebook authorization.

I have adjusted SecurityUtils to use ClassName vs realmName in determining what to use as you may have companies that decide to use their own custom realmname in shiro.ini and may not realize you cannot so using className is much safer.

Example - SecurityUtils
        String name = realm.getClass().getName();
        if (name.equals("org.apache.shiro.realm.text.IniRealm")) {
          allRoles = ((IniRealm) realm).getIni().get("roles");
          break;
        } else if (name.equals("org.apache.zeppelin.realm.LdapRealm")) {
          allRoles = ((LdapRealm) realm).getListRoles();
          break;
        }

Example - SecurityRestApi:
          String name = realm.getClass().getName();
          if (LOG.isDebugEnabled()) {
            LOG.debug("RealmClass.getName: " + name);
          }
          if (name.equals("org.apache.shiro.realm.text.IniRealm")) {
            usersList.addAll(getUserListObj.getUserList((IniRealm) realm));
            rolesList.addAll(getUserListObj.getRolesList((IniRealm) realm));
          } else if (name.equals("org.apache.zeppelin.realm.LdapGroupRealm")) {
            usersList.addAll(getUserListObj.getUserList((JndiLdapRealm) realm, searchText));
          } else if (name.equals("org.apache.zeppelin.realm.LdapRealm")) {
            usersList.addAll(getUserListObj.getUserList((LdapRealm) realm, searchText));
            rolesList.addAll(getUserListObj.getRolesList((LdapRealm) realm));
          } else if (name.equals("org.apache.zeppelin.realm.ActiveDirectoryGroupRealm")) {
            usersList.addAll(getUserListObj.getUserList((ActiveDirectoryGroupRealm) realm,
                searchText));
          } else if (name.equals("org.apache.shiro.realm.jdbc.JdbcRealm")) {
            usersList.addAll(getUserListObj.getUserList((JdbcRealm) realm));
          }

Please see feedback from previous PRs related to this JIRA:
apache#1513

### What type of PR is it?
[Improvement]

### Todos
* [ ] - Task

### What is the Jira issue?
https://issues.apache.org/jira/browse/ZEPPELIN-1472

### How should this be tested?
Update shiro.ini to use configuration similar to below:
# Sample LDAP configuration, for user Authentication, currently tested for single Realm
[main]
ldapADGCRealm = org.apache.zeppelin.realm.LdapRealm
ldapADGCRealm.contextFactory.systemUsername = CN=hdplookup,OU=hadoop,DC=hdpusr,DC=senia,DC=org
ldapADGCRealm.contextFactory.systemPassword = ldapBindPassword
ldapADGCRealm.searchBase = dc=hdpusr,dc=senia,dc=org
ldapADGCRealm.userSearchBase = dc=hdpusr,dc=senia,dc=org
ldapADGCRealm.groupSearchBase = dc=hdpusr,dc=senia,dc=org
ldapADGCRealm.authorizationEnabled = true
ldapADGCRealm.contextFactory.url = ldap://seniadc1.hdpusr.senia.org:3268
ldapADGCRealm.userSearchAttributeName = sAMAccountName
ldapADGCRealm.contextFactory.authenticationMechanism = simple
ldapADGCRealm.groupObjectClass = group
ldapADGCRealm.memberAttribute = member
ldapADGCRealm.rolesByGroup = hdpeng: admin, \
 hadoopusers: user

securityManager.realms = $ldapADGCRealm

sessionManager = org.apache.shiro.web.session.mgt.DefaultWebSessionManager

### If caching of user is required then uncomment below lines
#cacheManager = org.apache.shiro.cache.MemoryConstrainedCacheManager
#securityManager.cacheManager = $cacheManager

securityManager.sessionManager = $sessionManager
# 86,400,000 milliseconds = 24 hour
securityManager.sessionManager.globalSessionTimeout = 86400000
shiro.loginUrl = /api/login

[roles]
# 'admin' role has all permissions, indicated by the wildcard '*'
admin = *
user = *

[urls]
# anon means the access is anonymous.
# authcBasic means Basic Auth Security
# authc means Form based Auth Security
# To enfore security, comment the line below and uncomment the next one
#/api/version = anon
#/** = anon
/api/interpreter/** = authc, roles[admin]
/api/configurations/** = authc, roles[admin]
/api/credential/** = authc, roles[admin]
/api/login = authc
/api/login/logout = authc
/api/security/ticket = authc
/** = authc, roles[admin, user]

### Screenshots (if appropriate)

### Questions:
* Does the licenses files need update? n
* Is there breaking changes for older versions? n
* Does this needs documentation? y

merge latest commits

Author: gss2002 <[email protected]>
Author: gss2002 <[email protected]>

Closes apache#1614 from gss2002/ZEPPELIN-1472 and squashes the following commits:

d6a7cea [gss2002] ZEPPELIN-1472 - LdapRealm Additions based on Knox LdapRealm and support of using roles with LdapRealms. Also adjusted to use className and not actual name of the realm in shiro.ini. As using realmName in code could cause problems for people who want to use alternate names. Also migrated the LdapGroupRealm and ActiveDirectoryRealm to org.apache.zeppelin.realm packages per a recommendation.
1702cc5 [gss2002] Merge pull request #1 from apache/master