[lldb] Add detailed tests for the "disassemble" command

While we have some tests for this command already, they are very vague.
This is not surprising -- it's hard to make strict assertions about the
assembly if your input is a c++ source file. This means that the tests
can more-or-less only detect when the command breaks completely, and not
when there is a subtle change in meaning due to e.g. a code refactor --
which is something that I am getting ready to do.

This tests in this patch create binaries with well known data (via assembler
and yaml2obj). This means that we are able to make precise assertions
about the text that lldb is supposed to print. As some of the features
of this command are only available with a real process, I use a minidump
core file to create a sufficiently realistic process object.