Refactoring library to modernize code base. Fix #16

- Added data types everywhere + strict types
- Drop support for PHP < 8.1
- Renamed "Sasl" to "SASL"
- SASL factroy is now an enum

Cleanup + fixed tests of PR #19

Update README.md

Update README

Added support for PHP 8.3

Added support for SCRAM-SHA-*, SCRAM-SHA3-*

Merge pull request #9 from fabiang/php82

Added support for PHP 8.2 (closes #8)

Merge pull request #7 from dmolnarqu/patch-1

Throwable polyfill is missing methods

Quality of life

Allow strings containing zero to be passed to options