Replace print-at-pass-number cl::opt with print-before-pass-number (#76211)

The existing option prints the IR after the pass, but it's not clear
from its name. In this patch I change the option to print the IR before
the pass and change the name to make the behavior clear.

Printing the IR before the pass is slightly simpler than after as I
don't need to worry about printAfterPassInvalidated case. Either before
or after the pass would be ok for the original use case this option was
introduced for.