Support for extends Property in tsconfig.json

[bennobuilder]

Hello,

I am currently using your library, rollup-plugin-typescript-paths, and it works great for my use case. However, I've run into an issue where I need to handle the extends property in my tsconfig.json files.

Currently, if a tsconfig.json file extends another tsconfig.json file (as specified in the TypeScript Handbook), it appears that rollup-plugin-typescript-paths doesn't resolve the paths correctly according to the base tsconfig file. This is causing issues in my project setup, as I use the extends feature to avoid duplicating configuration across multiple tsconfig.json files.

I would appreciate it if extends support could be added to rollup-plugin-typescript-paths, allowing it to correctly resolve paths when a tsconfig.json file extends another one. This feature would greatly improve the utility of the plugin for projects that use the extends feature in their TypeScript configuration.

I have created a potential solution for this issue and submitted it in Pull Request #16. I look forward to your feedback and discussion on the proposed changes.

Thank you for your time and for maintaining this helpful project :)

cheers