install: suppress redundunt warnings with `depends_on` requirement

Remove kernel extensions specified in `uninstall :kext`.

When a formula depends on any requirements, they evaluated at most three times:
before locking, before installing dependent, before building formula.
When a non-fatal requirement is specified and thus evaluated three times,
mostly the same warning message is also emitted three times.

This change restricts printing the warning messages only when a bottle is
successfully installed or before building.
Since this timing is after the final dependency computation for each cases,
the warnings will be most useful to check what is not yet satisfied.

Fix flaky tests.

testbottest: don't use TEST_FIXTURE_DIR.

This isn't defined for formulae.

audit: don't check devel version_scheme/revision.

uninstall: ignore deprecations when uninstalling.

audit: check for HOMEBREW_PREFIX test path usage.

Handle `MethodDeprecatedError` because we want people to be able to
uninstall regardless of the content of their formula.

This is also not allowed.

As seen in https://github.com/Homebrew/homebrew-core/pull/6996.

bump-formula-pr: add --message option

utils/json: Replace OkJson with Ruby's core JSON.

tests: ignore test files in test/vendor/bundle

Removes OkJson from vendor/, as Ruby has included its own JSON
parser in corelib since 1.9.x and Homebrew is now guaranteed to be
running on 2.x+.

formula: update test_fixtures path

Fix regression caused by #1364.

For user-supplied PR message.

These are formulae-wide so doesn't make sense to iterate through these
for specs and get weird results.

As seem in https://github.com/Homebrew/homebrew-core/pull/6952.

cmd/list: follow aliases

This reverts commit 50c964df.

This was causing the flaky tests that #1508 started skipping.

This is the second time that `Formula.installed`'s cache has bitten
me with intermittent test failures, and I'd like it to be the last,
so I've made it so the cache is cleared automatically when a tab is
created. This _should_ mean that the cache is cleared any time it
needs to be, with the exception of when a Keg is created artificially
with no tab. I don't think there's anything I can do to automatically
handle that use-case, though.

Reorder and rename test files.

audit: only check previous formula version.

audit: check that there are any stable revisions.

For calculating the stable/devel versions this should be sufficient as
it's looking at `origin/master` so for a e.g. unmerged pull request this
will stop complaining about mistakes outside the pull request itself.

This will silence all warnings for historic version mistakes (i.e.
before these audit checks were all enabled) which is normally a bad
thing but as this case would rely on modifying history to complete is a
good one.

Fixes the exception if `revision_map[formula.stable.version]` is `nil`.