Move template configuration to source-mappings.json

[premun]

Context

During VMR synchronization, we create the component list and third party notices files based on the contents of the VMR.
These are created from templates stored in the SDK repo.
For the code flow, we should probably have these files in the VMR and point to them from source-mappings.json.

Each VMR branch can then define where these files are located and it will be easy to change this rather than having it hardcoded in darc.

Goal

Add settings for component list and third party notices templates to source-mappings.json and use those settings when we are generating these files.