Pass tags with INPUT_TAGS in docker bake job

[dbkr]

Truly hideous mess of shell to set both env vars in the prebuild step.

As the env var doesn't seem to be available to the actual executor but clearly must be available to the docker that it runs.

Checklist

• I have read through review guidelines and CONTRIBUTING.md.
• Tests written for new code (and old code if feasible).
• New or updated public/exported symbols have accurate TSDoc documentation.
• Linter and other CI checks pass.
• I have licensed the changes to Element by completing the Contributor License Agreement (CLA)

[dbkr]

Bypassing checks as the merge queue tests will currently fail downstream tests because we need element-hq/element-modules#269 and that can't merge because RoomView snapshots and docker bake is failing and develop is not updating.