Detailed argument errors

[SquidDev]

Compare Cobalt:

> string.sub(false)
stdin:1: bad argument: number expected, got boolean

with PUC Lua:

> string.sub(false)
stdin:1: bad argument #1 to 'sub' (string expected, got boolean)

The latter is obviously much more descriptive and useful. There's two things we should be doing here:

• Keeping argument indexes in the error message.
• Include error messages. See luaL_argerror for how it's done by Lua, but it's not entirely clear this is correct in the presence of tailcalls - we may need some additional sanity checks.

Also worth thinking about how, if at all, we can expose this to CC.