Clean up .gitignore, add Python.gitignore (#20613)
Clean up .gitignore, add Python.gitignore (#20613)

* Clean up .gitignore, add Python.gitignore

* Ignore `spack debug create-db-tarball` logs

* lib/ and var/ need to be tracked

* Add editor- and OS-specific ignores

* Add PyCharm ignores

* Add JetBrains editors like PyCharm
LLNL/spack,LLNL/spack,LLNL/spack,LLNL/spack,LLNL/spack