feat: expanded plugin unzipping

[CEbbinghaus]

Please tick as appropriate:

• [ ] I have tested this code on a steam deck or on a PC
• [ ] My changes generate no new errors/warnings
• [ ] This is a bugfix/hotfix
• [x] This is a new feature

Description

Current unzipping takes into account only a single structure of zip file in which the plugin is contained within a subfolder of the same name under the zip. This expands this to include both nested zipfiles (uploading artifacts from GHA) as well as the plugin within the root directory of the zip.

In particular this stops having to do this just to be able to publish a zip file through the Artifacts: https://github.com/CEbbinghaus/MicroSDeck/blob/6f3e010ec8e8f6b6d2e7a293541754a6215ccdef/.github/workflows/build.yml#L37-L47

[TrainDoctor]

If you feel this is ready to go to a testable PR please let me know.