feat: Remove `ParseUI`

[dplewis]

New Pull Request Checklist

• [x] I am not disclosing a vulnerability.
• [x] I am creating this PR in reference to an issue.

Issue Description

Building a UI has become a lot easier over the years, especially with SwiftUI; ParseUI today looks like an obsolete convenience that could be dropped from the Parse SDK. This is a breaking change.

Closes: https://github.com/parse-community/Parse-SDK-iOS-OSX/issues/1760 Closes: https://github.com/parse-community/Parse-SDK-iOS-OSX/issues/1729 Closes: https://github.com/parse-community/Parse-SDK-iOS-OSX/issues/1493 Closes: https://github.com/parse-community/Parse-SDK-iOS-OSX/issues/1406 Closes: https://github.com/parse-community/Parse-SDK-iOS-OSX/issues/1517

Approach

Remove ParseUI.

TODOs before merging

• [x] Add tests
• [x] Add changes to documentation (guides, repository pages, in-code descriptions)
• [x] Remove CI job

[parse-github-assistant[bot]]

Thanks for opening this pull request!

• 🎉 We are excited about your hands-on contribution!

[dplewis]

@mtrezza Codecov is broken

[JohnCaccavale]

Have the Privacy Manifests been added to the project yet? Worth including them here with this PR or best to do that in a separate PR?

[dplewis]

Have the Privacy Manifests been added to the project yet? Worth including them here with this PR or best to do that in a separate PR?

@JohnCaccavale They haven't been added. If they do it will be separate PR. Can you open an issue for it? I need to do some research on it.

[parseplatformorg]

🎉 This change has been released in version 4.0.0