Add selectors API to Linter() for fast-path filtering

[MichaelChirico]

Another optimization hit on by Gemini -- basically declaring a set of tokens without which we can skip running a linter. These tokens are necessary but not sufficient to find lints.

There is some decent overlap with #2449 -- for file-level linters, this approach is not quite so effective since the % of files skipped is less than the % of expressions skipped.

As of now, the rough improvement on just the linters currently included is about 35%:

linters <- list(
  any_duplicated_linter(),
  keyword_quote_linter(),
  list_comparison_linter(),
  seq_linter(),
  sort_linter(),
  string_boundary_linter(),
  unreachable_code_linter()
)
system.time(for (ii in 1:2) {
  lint_package("bit64", linters)
  lint_package("lintr", linters)
  lint_package("ggplot2", linters)
  lint_package("data.table", linters)
  lint_package("~/svn/r-devel/src/library/utils", linters)
})

# PR
#    user  system elapsed 
# 177.669   1.078 178.796 
# main
#    user  system elapsed 
# 271.533   1.008 272.598 

I can extend it to more linters if we think this is a worthwhile addition.

[codecov]

Codecov Report

✅ All modified and coverable lines are covered by tests.
✅ Project coverage is 99.25%. Comparing base (e6126ca) to head (2ff952a).

Additional details and impacted files

@@           Coverage Diff           @@
##             main    #3052   +/-   ##
=======================================
  Coverage   99.25%   99.25%           
=======================================
  Files         128      128           
  Lines        7369     7382   +13     
=======================================
+ Hits         7314     7327   +13     
  Misses         55       55           

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