Added TypeName and TypeUsage from OpenAPI Generator. (#1726)

Motivation:

The types are used by the code renderer that will be brought over from OpenAPI Generator
to the new gRPC Swift CodeGenLib.

Modifications:

Copied the TypeName, TypeUsage and some TypeName extensions that will be used
in the context of gRPC, and modified TypeName so it represents only the Swift path
of a type.

Result:

We will be able to bring over the Code Renderer and we will have types representations that can be used
by the service translator.

NOTICES.txt

@@ -60,9 +60,11 @@ This product uses derivations of swift-extras/swift-extras-base64 'Base64.swift'
 
 ---
 
-This product uses derivations of apple/swift-openapi-generator 'StructuredSwiftRepresentation.swift'.
+This product uses derivations of apple/swift-openapi-generator 'StructuredSwiftRepresentation.swift',
+'TypeName.swift', 'TypeUsage.swift' and 'Builtins.swift'.
     
     * LICENSE (Apache License 2.0):
       * https://github.com/apple/swift-openapi-generator/blob/main/LICENSE.txt
     * HOMEPAGE:
       * https://github.com/apple/swift-openapi-generator
+