Improve the execution pipeline splitting execution and schema generation

[Urigo]

Complete separation of execution and schema generation
- AVOID RELYING ON GRAPHQL-JS AS MUCH AS POSSIBLE
- Extracting Stitching executor like Federation’s
- In all handlers, executor and schema should be generated separately. mesh start should not generate GraphQLSchema unless it’s requested by introspection

• IDEA: Refactor Handlers by splitting artifacts generation and schema/executor generation #4057
• Resolvers Composition plugin doesn't work with GraphQL-like sources. #4202
• Avoid schema wrapping if possible and use executor/transforms approach with Envelop #4114