Buildozer - Allow operations across multiple files

Buildozer operations currently do not allow for changes across multiple files, it would be great if we could support this, either for moving rules/content between files, or things like copying attributes between files.

The team currently lacks bandwidth to expand on the functionality, but this issue is meant to be used for tracking of interest for this in case we have more bandwidth in the future.

No files, tests, or entry points are identified in the issue. Start by examining Buildozer's existing operations and how they select files, then define the supported cross-file cases. Done should include operations that can move rules or content between files and copy attributes between files.

Written by the indexing model from the issue text.