Remove the src-gen and xtend-gen folders from git

[ryanjob42]

This needs:

• Delete these folders from git
• Add lines to the .gitignore file so they won't be re-uploaded
• Make sure mvn package will still work locally and re-generate those files
• Make sure that the action runner still works and generates all the Java files (and JAR files?)

If any of the above doesn't work (mainly the last two steps), we'll need to update the pom.xml files (or something similar) to get everything working.