audit: check versioned formulae for keg_only :versioned_formula

[commitay]

• Have you followed the guidelines in our Contributing document?
• Have you checked to ensure there aren't other open Pull Requests for the same change?
• Have you added an explanation of what your changes do and why you'd like us to include them?
• Have you written new tests for your changes? Here's an example.
• Have you successfully run brew style with your changes locally?
• Have you successfully run brew tests with your changes locally?

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This is intended to enforce the (almost) default expectation that versioned @ formulae should be keg_only :versioned_formula.

Whitelisted:

• autoconf@2.13: suffixed
• bash-completion@2: conflicts with bash-completion, also whitelisted in conflicts cop
• gcc@* formulae: suffixed
• gnupg@1.4: suffixed
• lua@5.1: doesn't conflict with lua
• python@2: doesn't conflict with python

Stuff that should probably be fixed in core:

• antlr@2: renamed or keg_only antlr@2: make keg_only homebrew-core#33082
• autoconf@2.13: keg_only, (gjs depends on it) whitelisted
• gtksourceview@4: renamed, the other gtksourceview formulae aren't @ gtksourceview4: rename from gtksourceview@4 homebrew-core#33081

[MikeMcQuaid]

Nice work @commitay!