Remove operation dependency

[apotonick]

The dependency to trailblazer-operation is not necessary. Steps to remove it

1. Deprecate Result objects in all Policy() classes. I don't think anyone uses it. Use Activity::Deprecate.warn for the actual warning https://trailblazer.to/2.1/docs/internals#internals-core-developer-deprecate
2. Convert all tests from Operation to Activity::Railway and autoconvert.
3. Use <%= code_tabs %> for docs to show both versions. https://trailblazer.to/2.1/docs/internals#internals-core-developer-convert-operation-test

[yogeshjain999]

@apotonick Regarding 1st point, we actually use success? in controller to raise Pundit::NotAuthorizedError or pass around additional data.

I added lightweight replacement for Result in Policy for now, but let me know your thoughts!