add support for DWARF debugging symbols #94

Issue for discussion, raised by @olapiv, would be useful for coverage.

Emscripten supports adding DWARF debugging symbol in WASM.

It would be great to be able to access them from SWAM.

References:

• https://emscripten.org/docs/porting/Debugging.html
• Understanding DWARF+WebAssembly offsets WebAssembly/debugging#9

We use this issue to collect information and thoughts about this.