[lldb] Ignore non-address bits in "memory find" arguments

This removes the non-address bits before we try to use
the addresses.

Meaning that when results are shown, those results won't
show non-address bits either. This follows what "memory read"
has done. On the grounds that non-address bits are a property
of a pointer, not the memory pointed to.

I've added testing and merged the find and read tests into one
file.

Note that there are no API side changes because "memory find"
does not have an equivalent API call.

Reviewed By: omjavaid

Differential Revision: https://reviews.llvm.org/D117299