improve handling of progress in lint_dir, expose option show_progress

[MichaelChirico]

Closes #972

[codecov-commenter]

Codecov Report

Merging #2133 (9b2a2fa) into main (9bd015d) will increase coverage by 0.00%.
The diff coverage is 100.00%.

❗ Current head 9b2a2fa differs from pull request most recent head 6e31e3c. Consider uploading reports for the commit 6e31e3c to get more accurate results

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Files Changed	Coverage Δ
R/lint.R	98.88% <100.00%> (+0.02%)	⬆️

[AshesITR]

A nice feature extension would be to somehow show the current file in such a way that generated warnings() can be attributed.

[MichaelChirico]

A nice feature extension would be to somehow show the current file in such a way that generated warnings() can be attributed.

agree it's useful... not aware of a way to do so with {utils} progress bars. eventually I think we could allow the user to supply their own progress bar like {purrr} does. for now keeping things simple -- warnings/errors ideally don't happen often (they should usually be caught as lints), so I'm happy for the quick win for now.