install: search when formula isn't found.

If you do `brew install blah` it currently doesn't search for it. This
seems to be unintentional looking at this code as the exception thrown
by ARGV.formulae.each is not caught and handled. Instead, let's handle
this case and provide a little more usability around our taps.

Closes #31761.

Signed-off-by: Mike McQuaid <mike@mikemcquaid.com>