support replacing inputModel with SubResource in management generator. (Azure#51593)

* support replacing inputModel with SubResource in management generator.

Author: haiyuazhang

eng/packages/http-client-csharp-mgmt/generator/Azure.Generator.Management/src/Primitives/KnownManagementTypes.cs

@@ -44,6 +44,7 @@ internal class KnownManagementTypes
             ["Azure.ResourceManager.CommonTypes.OperationStatusResult"] = typeof(OperationStatusResult),
             ["Azure.ResourceManager.CommonTypes.SystemData"] = typeof(SystemData),
             ["Azure.ResourceManager.CommonTypes.UserAssignedIdentity"] = typeof(UserAssignedIdentity),
+            ["Azure.ResourceManager.Models.SubResource"] = typeof(SubResource),
         };
 
         private static readonly Dictionary<string, CSharpType> _idToPrimitiveTypeMap = new Dictionary<string, CSharpType>()

eng/packages/http-client-csharp-mgmt/generator/Azure.Generator.Management/src/Providers/OperationMethodProviders/PageableOperationMethodProvider.cs

@@ -28,6 +28,8 @@ internal class PageableOperationMethodProvider
         private readonly bool _isAsync;
         private readonly CSharpType _itemType;
         private readonly ResourceOperationKind _methodKind;
+        private readonly MethodSignature _signature;
+        private readonly MethodBodyStatement[] _bodyStatements;
 
         public PageableOperationMethodProvider(
             TypeProvider enclosingType,
@@ -47,13 +49,15 @@ public PageableOperationMethodProvider(
             _isAsync = isAsync;
             _itemType = itemType;
             _methodKind = methodKind;
+            _signature = CreateSignature();
+            _bodyStatements = BuildBodyStatements();
         }
 
         public static implicit operator MethodProvider(PageableOperationMethodProvider pageableOperationMethodProvider)
         {
             return new MethodProvider(
-                pageableOperationMethodProvider.CreateSignature(),
-                pageableOperationMethodProvider.BuildBodyStatements(),
+                pageableOperationMethodProvider._signature,
+                pageableOperationMethodProvider._bodyStatements,
                 pageableOperationMethodProvider._enclosingType);
         }
 
@@ -95,7 +99,7 @@ protected MethodBodyStatement[] BuildBodyStatements()
             {
                 _restClientInfo.RestClientField,
             };
-            arguments.AddRange(_contextualPath.PopulateArguments(This.As<ArmResource>().Id(), requestMethod.Signature.Parameters, contextVariable, _convenienceMethod.Signature.Parameters));
+            arguments.AddRange(_contextualPath.PopulateArguments(This.As<ArmResource>().Id(), requestMethod.Signature.Parameters, contextVariable, _signature.Parameters));
 
             // Handle ResourceData type conversion if needed
             if (IsResourceDataType(_itemType))