Importing projects site projects from .sb3 files

[rammodhvadia]

What's changed?

• Added an sb3 parser to extract scratch component json and asset files from .sb3 file
• Added new functions to import assets from sb3 files in scratch_asset_importer.rb
• Updated ProjectImporter to import scratch component and asset for code_editor_scratch projects
• Updated UploadJob to process .sb3 files
• Updated FileSystemProject to accept .sb3 files

[github-actions]

Test coverage

91.72% line coverage reported by SimpleCov.
Run: https://github.com/RaspberryPiFoundation/editor-api/actions/runs/27402013521

[cla-bot]

We require contributors to sign our Contributor License Agreement, and we don't have you on file. In order for us to review and merge your code, please complete this form and we'll get you added and review your contribution as soon as possible.