Regex: Add regex_match_all_c and regex_match_all natives (by Nextra)
Regex: Remove regex_match_ex and RegexError tag, change regex_match_all to use flags and update documentation.

- regex_match_ex was kind of duplicated.
- regex_match_all uses now integer flags (header like regex_compiler_ex)
- Removed RegexError tag to allow old natives to use these constants without mismatch tag error.
- Made all error params optional