Conflict resolution of upstream merge 2.5.1

[cloudw]

Resolving conflicts from upstream.

Most of conflicts are result of netflix/metaflow embracing black formatting 🎉

Major changes that resulted in code changes:

• Vendor click as dependency for Metaflow Netflix/metaflow#929 Related imports in KFP plug-in are rewrote
• New Datastore abstraction for Metaflow Netflix/metaflow#580 All datastore usage in KFP plug-in are rewrote. This touches all decorator, kfp cli and kfp foreach splits.
• Coverage functionalities are removed as it is removed from upstream as well. ⚠️ May result in test coverage drop for customers using flow in unit tests.
• Other conflict resolutions

[alexlatchford]

I'd say we get the tests working before merging this, looks like there are still some <<< lines in there based on the test details :)

[cloudw]

Closing in favor of merge_upstream_2_5_3 branch