Added support for forced yield and timeouts

[timstableford]

• This allows registering a hook that runs every X instructions to force a yield. The hook will be run even if the Lua program is stuck in a loop.
• The global wasn't being correctly closed and memory free'd, fixed that.
• Use finalization registry when yielding a promise to ensure timed out or abandoned yields are still cleaned up.

Resolves https://github.com/ceifa/wasmoon/issues/19