tests: skip gracefully when the tested binary's own package isn't installed

[imp]

Summary

pkgbase splits programs and their tests into separate packages (e.g.
unifdef/yacc/indent/file2c -> toolchain, jail -> jail, etc), while their
tests always land in the generic tests package. Installing just the
tests package therefore leaves these suites unable to find the binary
they exercise, and they fail confusingly instead of skipping.

Rather than force all packages to be installed for the tests package,
make the tests cope with the missing packages. Add require.progs (or,
for TAP/PLAIN-style suites with no atf_set hook: TEST_METADATA
required_programs) for the binary under test in: bectl, certctl,
ctfconvert, dhclient, file2c, indent, ipfw, jail, lastcomm, mixer,
newsyslog, nvmecontrol, pfctl, praudit, sa, syslogd, tunefs, unifdef,
yacc, ztest.

I skipped adding data for all the binaries in the base runtime
package for simplicity.

Assisted-by: Claude Code (Sonnet 5)
Sponsored by: Netflix

Test Plan

Testing is being done with VM images with fewer packages installed, though not all combos.

[ngie]

Side thought: it would be nice if these were actually broken down into subpackages, e.g., indent-tests, etc.

[imp]

In D58262#1336336, @ngie wrote:

Side thought: it would be nice if these were actually broken down into subpackages, e.g., indent-tests, etc.

Not sure about this, but beyond the scope.

I also have one or two other changes to make this work I'll roll in before committing.

[ngie]

In D58262#1337132, @imp wrote:

In D58262#1336336, @ngie wrote:

Side thought: it would be nice if these were actually broken down into subpackages, e.g., indent-tests, etc.

Not sure about this, but beyond the scope.

I also have one or two other changes to make this work I'll roll in before committing.

Understandably so. I was thinking out loud because it's something that should be put down in our backlog, as an iterative next step towards breaking down how base is packaged.