In accordance with [this advisory](https://github.blog/changelog/2020-10-01-github-actions-deprecating-set-env-and-add-path-commands/) it's recommended we moved to a different scheme of setting env vars and updating PATH.
* Add GDB test * rm stray test resource * use object:🧝:* structures * install gdb on CI
* add lldb runner * don't build wasmtime * use brew's lldb * disable for macos * set LLDB on linux * re-org gh actions and cfg * address feedback