This change introduces a new HostDefinedIsCodeLike internal slot, this is used to allow evaluating certain objects.

This change also provides the full code string,
the compilation type and the original arguments, to the host hook HostEnsureCanCompileStrings.

- Use a HostGetCodeForEval host hook rather than an internal slot.
- Host hook returns a string or unknown and that string is what is evaluated not ToString.
- Don't pass constructed codeString to HostEnsureCanCompileStrings

- PerformEval _direct_ is now an enum.
- Reordered steps for handling objects and strings in PerformEval.
- Fixed usage of _x_ rather than _xStr_
- Change new host hook to return String or ~no-code~

…teDynamicFunction, it no longer needs moving as it doesn't need the source string.