Add backtrace support

[kateinoigakukun]

This PR adds minimal support to display backtrace for a trap with minimal performance overhead.

$ cat t.wat
(module
  (memory (export "memory") 1)
  (func $foo (result i32)
    unreachable
  )
  (func $bar (result i32)
    (call $foo)
  )
  (func (export "_start")
    (call $bar)
    (drop)
  )
)
$ wat2wasm --debug-name t.wat
$ wasmkit-cli run t.wasm
Error: Trap: unreachable
    0: foo
    1: bar
    2: _start

TODO

• Show binary source offset (we need to build address map during the Translator pass)
• Host/guest interleaving stack trace