(SCHEMA, CLI) Update dsc schema to return extension schemas

Prior to this change, the `dsc schema` command did not include
options to return the JSON Schema for either the extension
manifest or a **Discover** extension operation result output
object.

This change ensures users can call the command to review those
JSON Schemas.

Author: michaeltlombardi

dsc/src/args.rs

@@ -270,4 +270,6 @@ pub enum DscType {
     ConfigurationGetResult,
     ConfigurationSetResult,
     ConfigurationTestResult,
+    ExtensionManifest,
+    ExtensionDiscoverResult
 }

dsc/src/util.rs

@@ -4,6 +4,8 @@
 use crate::args::{DscType, OutputFormat, TraceFormat};
 use crate::resolve::Include;
 use dsc_lib::configure::config_result::ResourceTestResult;
+use dsc_lib::extensions::discover::DiscoverResult;
+use dsc_lib::extensions::extension_manifest::ExtensionManifest;
 use dsc_lib::{
     configure::{
         config_doc::Configuration,
@@ -176,6 +178,12 @@ pub fn get_schema(dsc_type: DscType) -> RootSchema {
         DscType::ConfigurationTestResult => {
             schema_for!(ConfigurationTestResult)
         },
+        DscType::ExtensionManifest => {
+            schema_for!(ExtensionManifest)
+        },
+        DscType::ExtensionDiscoverResult => {
+            schema_for!(DiscoverResult)
+        },
     }
 }