patch 9.1.1906: filetype: not all Ruby files are recognized

patch 9.1.1906: filetype: not all Ruby files are recognized

Problem:  filetype: not all Ruby files are recognized
Solution: Detect *.rbi and Brewfile as ruby filetype
          (botantony).

- `rbi` is a file extension used by Sorbet, typechecker for Ruby:
   https://sorbet.org/docs/rbi

- `Brewfile` is a bundler file for Homebrew package manager:
   https://docs.brew.sh/Brew-Bundle-and-Brewfile

closes: #18697

Signed-off-by: botantony <antonsm21@gmail.com>
Signed-off-by: Christian Brabandt <cb@256bit.org>