[SPARK-3566] [BUILD] .gitignore and .rat-excludes should consider Windows cmd file and Emacs' backup files

Author: Kousuke Saruta <sarutak@oss.nttdata.co.jp>

Closes #2426 from sarutak/emacs-metafiles-ignore and squashes the following commits:

a306020 [Kousuke Saruta] Merge branch 'master' of git://git.apache.org/spark into emacs-metafiles-ignore
6a0a5eb [Kousuke Saruta] Added cmd file entry to .rat-excludes and .gitignore
897da63 [Kousuke Saruta] Merge branch 'master' of git://git.apache.org/spark into emacs-metafiles-ignore
8cade06 [Kousuke Saruta] Modified .gitignore to ignore emacs lock file and backup file