- Added NadekoBot.Generators projects which will contain source generators

- Implemented initial version of the response strings source generator
  - Creates a class with property names equivalent to key names in responses.en-US.json
  - Each Property has struct type (with generic type parameters matching the number of string format placeholders) for type safe GetText implementation
  - Struct types are readonly refs as they should be ephermal, and only used to pass string keys to GetText

src/NadekoBot/Common/NadekoModule.cs

@@ -31,6 +31,9 @@ namespace NadekoBot.Modules
 
         protected string GetText(string key) =>
             Strings.GetText(key, _cultureInfo);
+        
+        protected string GetText(in LocStr key) =>
+            Strings.GetText(key.Key, _cultureInfo);
 
         protected string GetText(string key, params object[] args) =>
             Strings.GetText(key, _cultureInfo, args);