Debugging support for multi-memory Wasm (DWARF)

[yurydelendik]

Wasmtime currently generate native DWARF based on the assumption that Wasm module has at most one memory. Beside support of multi-memory addressing in the WebAssemby DWARF spec itself, we need to fix the translation for native DWARF:

• Spec for multi-memory address location
• Fix DWARF translation
  • in debug_builtins (see Utility methods for artificial debug types in the generated DWARF #1482)
  • in utils.rs add_internal_types to generate proper WasmtimeVMContext

[yurydelendik]

Trying to spec at yurydelendik/webassembly-dwarf#10