Deprecate Validated

[nomisRev]

Suggested migration process using ReplaceWith:

• Migrate all methods, zip -> zipOrAccumulate, getOrElse, etc to their toEither() equivalents using Replace in entire project action from IntelliJ
• Migrate all functions returning Validated or ValidatedNel, and their invalid, invalidNel(), etc constructors. (This piece can potentially be scripted like https://gist.github.com/nomisRev/e01ddc354c84b8b626c23d024706b916)
• Replace in entire project Either.toEither() intermediate method

=> Now all Validated usage should be somewhat automatically be replaced in the project in 3~4 steps.
Refactoring looks like this:

Validated.Refactor.2.mov

Issues:

• For some reason typealias ValidatedNel doesn't add the import
• toValidated is unresolved after the refactor. We could remove it from ReplaceWith, making it an incorrect replacement. Then we might also consider removing the intermediate calls to toEither()`.

Separately also investigating if we can automate this further using OpenRewrite to offer a smooth and pain-free migration process.

[github-actions]

Kover Report

File	Coverage [59.26%]
arrow-libs/core/arrow-core/src/commonMain/kotlin/arrow/core/Either.kt	57.04%
arrow-libs/core/arrow-core/src/commonMain/kotlin/arrow/core/Validated.kt	62.17%
arrow-libs/core/arrow-core/src/commonMain/kotlin/arrow/core/raise/Raise.kt	58.70%

Total Project Coverage	43.82%

[serras]

Awesome dev experience :)

[nomisRev]

cc\ @Zordid

This PR changes E.toEitherNel to E.leftNel as you reported.

[nomisRev]

Ooof, thanks @franciscodr! Bunch of copy-paste mistakes 🙈

[nomisRev]

Any feedback, or comments on the PR still very welcome 🙏 Thank you ☺️