Consider linting rex(paste(...))

[MichaelChirico]

From comment thread:

Originally posted by @AshesITR in #2190 (comment)

[MichaelChirico]

FWIW I don't see any usage like this outside {lintr} itself:

https://github.com/search?q=lang%3AR+%2F%28%5E%7C%5B%5Ea-z%5D%29rex%5B%28%5Dpaste0%3F%5B%28%5D%2F&type=code

Closing as too obscure unless we get an outside request