Refactor debug library to use object:🧝:* (#1860)

* Add GDB test

* rm stray test resource

* use object:🧝:* structures

* install gdb on CI

.github/actions/define-llvm-env/action.yml

@@ -1,5 +1,5 @@
 name: 'Set up a DWARFDUMP env'
-description: 'Set up a DWARFDUMP env (see tests/debug/dump.rs)'
+description: 'Set up a DWARFDUMP env (see tests/all/debug/dump.rs)'
 
 runs:
   using: node12