add support for `jSignalsInfo` packet

DS2 does not support the `jSignalsInfo` packet documented. This packet doesn't appear in the lldb documentation, but was added to lldb [here](https://github.com/llvm/llvm-project/commit/98d0a4b39a89ad4d667d9150a008a0c36be94f1f) and we can see it being sent to ds2 during testing.