TypeORM: Add support for creating custom TypeORM repositories

Add support for creating custom TypeORM repositories with custom methods (e.g. to implement bookRepo.findByTitle(title)) and other functionalities.

The issue names TypeORM custom repositories and methods such as bookRepo.findByTitle(title), but it identifies no files, tests, or entry points. Start by locating the existing TypeORM repository integration and its repository creation path, then determine the API and dependency-injection behavior required. Done means custom repositories can be created with custom methods and other requested functionality, with coverage for the supported behavior.

Written by the indexing model from the issue text.