Fix failures in passing or converting permissions

[EmmaZhu]

Packages impacted by this PR

@azure/storage-file-datalake

Issues associated with this PR

Describe the problem that is addressed by this PR

For pathClient.setPermission interface, following is doc for permission string format:

    Optional and only valid if Hierarchical Namespace is enabled for the account. Sets POSIX access permissions for the file owner, the file owning group, and others. Each class may be granted read(4), write(2), or execute(1) permission. Both symbolic (rwxrw-rw-) and 4-digit octal notation (e.g. 0766) are supported. 
    The sticky bit is also supported and in symbolic notation, its represented either by the letter t or T in the final character-place depending on whether the execution bit for the others category is set or unset respectively (e.g. rwxrw-rw- with sticky bit is represented as rwxrw-rwT. A rwxrw-rwx with sticky bit is represented as rwxrw-rwt), absence of t or T indicates sticky bit not set. In 4-digit octal notation, its represented by 1st digit (e.g. 1766 represents rwxrw-rw- with sticky bit and 0766 represents rwxrw-rw- without sticky bit). 
  Invalid in conjunction with x-ms-acl.

The SDK currently only support 't', but doesn't support 'T'. This PR is to add support for 'T'.

What are the possible designs available to address the problem? If there are more than one possible design, why was the one in this PR chosen?

Are there test cases added in this PR? (If not, why?)

Provide a list of related PRs (if any)

Command used to generate this PR:**(Applicable only to SDK release request PRs)

Checklists

• Added impacted package name to the issue description
• Does this PR needs any fixes in the SDK Generator? No
• Added a changelog (if necessary)

[azure-sdk]

API change check

API changes are not detected in this pull request.