Feature: #72337 - Charset Conversion Autodetection

See Issue #72337

Description

The Charset Converter which is used to handle multi-byte charset conversions now always uses mbstring. In case mbstring is not present a polyfill will kick in.

Impact

The options $TYPO3_CONF_VARS['SYS'][t3lib_cs_utils] and $TYPO3_CONF_VARS[SYS][t3lib_cs_convMethod] have no effect anymore and can be removed.