Upgrade path to plugin attributes

What is required to support both, technically speaking?

Here is the Drupal core meta issue that shows the progress for all core annotation types, and their conversion status: 📌 [meta] Convert all core plugin types to attribute discovery Postponed

This Drupal Answers thread provides some good guidance on how to convert annotations to attributes using Rector: https://drupal.stackexchange.com/questions/321008/how-to-use-drupal-rect...

I've started some of this process for core annotations locally. I will push a branch up soon and lay out next steps...

Talked through strategy with @paul121 today, and this is the tentative plan:

1. Merge 3.x-rector branch (PR: https://github.com/farmOS/farmOS/pull/901)
2. 3.x-attributes branch
   1. Convert all annotations to attributes that can be in Drupal 10
   2. Add support for attributes in farmOS plugin types in 3.x
   3. Add rector config to enforce attributes in new PRs
3. 4.x-attributes branch
   1. Convert all annotations to attributes that can be in Drupal 11 (with rector config to enforce)
   2. Deprecate farmOS plugin annotations in 4.x (for removal in 5.x)

Merge 3.x-rector branch (PR: https://github.com/farmOS/farmOS/pull/901)

Done!

1. Convert all annotations to attributes that can be in Drupal 10
2. Add rector config to enforce attributes in new PRs

Opened a PR for these two pieces: https://github.com/farmOS/farmOS/pull/908

Add support for attributes in farmOS plugin types in 3.x

Started a 3.x-farm-attributes branch for this: https://github.com/mstenta/farmOS/tree/3.x-farm-attributes

It only adds the enforcement logic to rector.php. We still need to add support for attributes to all of our custom plugin types.

Convert all annotations to attributes that can be in Drupal 11 (with rector config to enforce)

Started a 4.x-attributes branch for this: https://github.com/mstenta/farmOS/tree/4.x-attributes

This includes ConfigEntityType, ContentEntityType, and MigrateSource, which did not have attributes support in Drupal 10.

Deprecate farmOS plugin annotations in 4.x (for removal in 5.x)

This can be added to the 4.x-attributes branch once we add support for attributes to farmOS plugin types in 3.x.