Add globbing support to exclusions

[AshesITR]

Maybe we should look into allowing wildcard exclusions based on file names?

exclusions: list("*.Rmd" = "library_call_linter"))

seems readable and concise for your usecase @IndrajeetPatil. WDYT?

Originally posted by @AshesITR in #2161 (comment)

[MichaelChirico]

Note #1554 -- I think they're related but not the same, so it would help to disambiguate

[AshesITR]

The Sys.glob() approach will not work with this issue; otherwise they seem fairly similar. Thanks for referencing.