Add RelocatingClassLoader to fix custom ruleset JARs

[haysmike]

Fixes #786

Description

9de656b broke custom rulesets JARs because the plugin now relocates org.jetbrains.kotlin to shadow.org.jetbrains.kotlin.

This PR transforms custom ruleset bytecode at load time using IntelliJ's bundled ASM library, remapping package references to match the shadow-relocated packages.

Testing

1. Built the plugin

   ./gradlew clean build
   ./create-ktlint-plugin-zip.sh

2. Installed in Android Studio (using "Install Plugin from Disk...") and restarted IDE
3. Double-checked configuration with Compose rules:
   
4. Verified that I don't get any error popups, and that I see expected lint warnings in my composables:
   

Note to reviewer(s)

I'm not an expert with IntelliJ plugin development or Java internals, so please feel free to redirect me towards better approaches. Also let me know if there's a unit test you'd like to see here - I wasn't sure how to test this in a reasonable way.

Thanks for all your work on ktlint!

[paul-dingemans]

Thank you so much for this contribution. I couldn't wrap my head around it myzelf. The code is clear, although I would have less intermediate variables myself. There is no need to change that though.

[haysmike]

@paul-dingemans thanks for the feedback! I think I've addressed all your comments.

less intermediate variables myself

I generally prefer that too. I did a pass and inlined everything that I could (I think).

Feel free to make any edits you like as well - I have the "Allow edits by maintainers" option on 🙂

[paul-dingemans]

I will release a beta version tomorrow. It would be great if you can validate that version once more. After that I can release the stable version. It can take up to business days before it is approved by Jetbrains.

[paul-dingemans]

Version 0.30.4.-0-beta-1 has been published

[haysmike]

@paul-dingemans The beta build works great for me! 🚀 🚀 🚀 🚀

[paul-dingemans]

@paul-dingemans The beta build works great for me! 🚀 🚀 🚀 🚀

Thanks for confirmation,. Stable release is being published now. It might take up to two business days before it is approved by JetBrains.

Once more, thanks for contributing!