Codegen: Also generate a definition file for .graphql fils

Similar to [typed-css-modules ](https://github.com/Quramy/typed-css-modules) the codegen can generate declaration files for existing query files that has list of exported queries and mutations.

This will help TypeScript enforce correct names when importing queries from `.graphql` file using `"graphql-tag/loader"`.

Start by locating the codegen entry point that processes existing .graphql query files and review how generated outputs are named. Define the declaration-file output for exported queries and mutations, then verify that TypeScript can enforce valid imports through graphql-tag/loader. The issue names no specific files or tests, so the repository’s codegen and test structure will need to be mapped first.

Written by the indexing model from the issue text.