Add tests for the other variants of BreakpointCreateBySourceRegex.

I added some tests for the case where the breakpoints take immediately
to the extant test case, and made a new test case for when the source
regex breakpoint will be set in a dlopen-ed library.

I also noticed when doing this that "lldbutil.run_to_source_breakpoint
can't handle the case where the breakpoint will be in a dlopen-ed
library, since it requires the breakpoint to have at least 1 location
before run.  I fixed that by adding a parameter to say whether a
before run location is expected.

Differential Revision: https://reviews.llvm.org/D111920