Json schema generator (#46)

* add json schema generator

* add props & targets, cli tool

* fix incorrect type check in attribute factory
implement enum hints

* update pipeline

* undo namespace cleanup

* fix formatting

* move from InternalsVisibleTo to public types

* clean test app

Author: SleepWellPupper

TestApp/Program.cs

@@ -1,22 +1,7 @@
-using RhoMicro.CodeAnalysis;
-
 internal class Program
 {
     private static void Main(String[] _0)
     {
 
     }
 }
-
-[UnionType<ErrorCode, MultipleUsersError, User>(Storage = StorageOption.Value)]
-readonly partial struct GetUserResult;
-
-sealed record User(String Name);
-
-enum ErrorCode
-{
-    NotFound,
-    Unauthorized
-}
-
-readonly record struct MultipleUsersError(Int32 Count);