Revert "[LLDB] Add DynamicLoaderWasmDYLD plugin for WebAssembly debugging"

This patch has a couple of outstanding issues. The test is not python3
compatible, and it also seems to fail with python2 (at least under some
circumstances) due to an overambitious assertion.

This reverts the patch as well as subsequent fixup attempts:
014ea933,
f5f70d1c.
4697e701.
5c15e8e6.
3ec28da6.