Support more advanced glob matching for CODEOWNERS

What does this MR do and why?

This MR updates the CODEOWNERS parsing logic to support more complex patterns.

Previous app/**/*token* pattern didn't match

flags = ::File::FNM_DOTMATCH | ::File::FNM_PATHNAME | ::File::FNM_EXTGLOB
path = 'app/assets/javascripts/access_tokens/index.js'
pattern = 'app/**/*token*'
::File.fnmatch?(pattern, path, flags)
=> false

New app/**/{*token*/**/*,*token*} pattern does match

flags = ::File::FNM_DOTMATCH | ::File::FNM_PATHNAME | ::File::FNM_EXTGLOB
path = 'app/assets/javascripts/access_tokens/index.js'
pattern = 'app/**/{*token*/**/*,*token*}'
::File.fnmatch?(pattern, path, flags)
=> true

Related: !84141 (merged)

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