Add validators and services for Product Galleries and Product Tags

- Implemented Create, Delete, Get, and Update validators for Product Galleries.
- Added Create, Delete, Get, and Update validators for Product Tags.
- Created service classes for handling Discount Categories, Discount Orders, Discount Products, Discount Shopping Cart, Product Categories, Product Galleries, and Product Tags.
- Each service class integrates with CQRS for command and query handling.
- Established mapping profiles for Product Galleries.

src/CMSMicroservice.Protobuf/Protos/productcategory.proto

@@ -0,0 +1,98 @@
+syntax = "proto3";
+
+package productcategory;
+
+import "public_messages.proto";
+import "google/protobuf/empty.proto";
+import "google/protobuf/wrappers.proto";
+import "google/protobuf/duration.proto";  
+import "google/protobuf/timestamp.proto";
+import "google/api/annotations.proto";
+
+option csharp_namespace = "CMSMicroservice.Protobuf.Protos.ProductCategory";
+
+service ProductCategoryContract
+{
+    rpc CreateNewProductCategory(CreateNewProductCategoryRequest) returns (CreateNewProductCategoryResponse){
+        option (google.api.http) = {
+            post: "/CreateNewProductCategory"
+            body: "*"
+        };
+    };
+    rpc UpdateProductCategory(UpdateProductCategoryRequest) returns (google.protobuf.Empty){
+        option (google.api.http) = {
+            put: "/UpdateProductCategory"
+            body: "*"
+        };
+    };
+    rpc DeleteProductCategory(DeleteProductCategoryRequest) returns (google.protobuf.Empty){
+        option (google.api.http) = {
+            delete: "/DeleteProductCategory"
+            body: "*"
+        };
+    };
+    rpc GetProductCategory(GetProductCategoryRequest) returns (GetProductCategoryResponse){
+        option (google.api.http) = {
+            get: "/GetProductCategory"
+            
+        };
+    };
+    rpc GetAllProductCategoryByFilter(GetAllProductCategoryByFilterRequest) returns (GetAllProductCategoryByFilterResponse){
+        option (google.api.http) = {
+            get: "/GetAllProductCategoryByFilter"
+            
+        };
+    };
+}
+message CreateNewProductCategoryRequest
+{
+    int64 product_id = 1;
+    int64 category_id = 2;
+}
+message CreateNewProductCategoryResponse
+{
+    int64 id = 1;
+}
+message UpdateProductCategoryRequest
+{
+    int64 id = 1;
+    int64 product_id = 2;
+    int64 category_id = 3;
+}
+message DeleteProductCategoryRequest
+{
+    int64 id = 1;
+}
+message GetProductCategoryRequest
+{
+    int64 id = 1;
+}
+message GetProductCategoryResponse
+{
+    int64 id = 1;
+    int64 product_id = 2;
+    int64 category_id = 3;
+}
+message GetAllProductCategoryByFilterRequest
+{
+    messages.PaginationState pagination_state = 1;
+    google.protobuf.StringValue sort_by = 2;
+    GetAllProductCategoryByFilterFilter filter = 3;
+}
+message GetAllProductCategoryByFilterFilter
+{
+    google.protobuf.Int64Value id = 1;
+    google.protobuf.Int64Value product_id = 2;
+    google.protobuf.Int64Value category_id = 3;
+}
+message GetAllProductCategoryByFilterResponse
+{
+    messages.MetaData meta_data = 1;
+    repeated GetAllProductCategoryByFilterResponseModel models = 2;
+}
+message GetAllProductCategoryByFilterResponseModel
+{
+    int64 id = 1;
+    int64 product_id = 2;
+    int64 category_id = 3;
+}