Problem: filetype: .envrc & .prettierignore not recognized
Solution: Detect '.envrc' as shell and '.prettierignore' as gitignore
filetype (Tyler Miller)
Support ft detection for `.envrc` files used by direnv, and
`.prettierignore` files used by prettier.
closes: vim/vim#15053resolves: neovim/neovim#2940549012cd8c2
Co-authored-by: Tyler Miller <tmillr@proton.me>