feat: Add Protobuf definitions for Network Membership service

- Introduced `networkmembership.proto` with RPC methods for retrieving user network tree, statistics, and position.
- Implemented HTTP annotations for gRPC transcoding in the service methods.
- Added support for Google API annotations in `annotations.proto` and `http.proto`.
- Created `ConfigureServices.cs` to register FluentValidation for the Protobuf services.
- Updated project file to include necessary dependencies for gRPC and Protobuf.

src/Protobufs/FrontOffice.BFF.ClubMembership.Protobuf/ConfigureServices.cs

@@ -0,0 +1,13 @@
+using FluentValidation;
+using System.Reflection;
+
+namespace Microsoft.Extensions.DependencyInjection;
+
+public static class ConfigureServices
+{
+    public static IServiceCollection AddClubMembershipProtobufServices(this IServiceCollection services)
+    {        
+        services.AddValidatorsFromAssembly(Assembly.GetExecutingAssembly());        
+        return services;
+    }    
+}