Add utility to migrate settings

[Sidsector9]

Description of the Change

PR adds migration script to migrate existing configured settings to new feature first settings introduced in classifAI v3.

Closes #670

How to test the Change

1. Clone this repo
2. Checkout to trunk branch, and build the plugin files
3. Activate the plugin and configure all of the AI providers.
4. Checkout to this PR branch. upkeep/670
5. Verify that you see the notice about ClassifiAI settings migrated and changes in v3
6. Go to Tools > ClassifAI and make sure all settings migrated properly.
7. Validate each features are working properly.

Changelog Entry

Added - Tool to migrate feature settings from versions < 3.0.0

Credits

Props @dkotter @Sidsector9 @iamdharmesh

Checklist:

• I agree to follow this project's Code of Conduct.
• I have updated the documentation accordingly.
• I have added tests to cover my change.
• All new and existing tests pass.

[github-actions]

@Sidsector9 thanks for the PR! Could you please fill out the PR template with description, changelog, and credits information so that we can properly review and merge this?

[iamdharmesh]

Note: E2E tests are failing due to some issue in wp-env.

[qasumitbagthariya]

QA Update ⚠️

---

@iamdharmesh Thanks for the PR.

I have checked migration with branch upkeep/670 and I'm getting some issue with migration.

I tried the same steps mentioned in the PR description and noticed that sometimes the migration is not working as expected.

Please check the video below, and let me know if you need any help to reproduce the issue.

Issue video:
https://drive.google.com/file/d/1YTHY4U0qRHKRnqH6kcpLnGdLbQo_3WxV/view?usp=drive_link

[dkotter]

Tested this and all seemed to work fine for me. There is potential for some confusion as we've rearranged some settings and changed how the role and user based access works (no longer showing extra checkboxes) but that all looks fine to me and the main things (like API keys) all come over correctly

[dkotter]

One other thing to consider is we aren't deleting any of the old settings that are stored in options. I think that's okay for now, as it allows users to access that if something does go wrong in the migration process. But we probably want to look at cleaning that up in a release or two.