example/android/app/.cxx should be in .gitignore

[freemansoft]

Describe the bug .cxx directory should be ignored and not offered for addition to the repository

To Reproduce Steps to reproduce the behavior:

1. Run the android example using android studio
2. example/android/app/.cxx/Debug... will be created
3. The .cxx directory will be offered up to be added to the source tree (I see this in VSCode)

Expected behavior .cxx should never be added

Smartphone / tablet n/a

Peripheral device n/a

Additional context I use VSCode for flutter work but ran this with android studio while troubleshooting gradle.