Fixed phpunit test runs with encoding test run and not resetting the
subsitute character back to default
Note: There are mime encoding failures for php 7.4 and 8.0 and one ACL
login failure test for php 7.4
Language\Encoding::__mbMimeEncode -> Convert\MimeEncode::__mbMimeEncode
Langauge\Encoding::checkConvertEncoding -> Check\Encoding::checkConvertEncoding
Langauge\Encoding::setErrorChar -> Check\Encoding::setErrorChar
Langauge\Encoding::getErrorChar -> Encoding::getErrorChar
Langauge\Encoding::convertEncoding -> Convert\Encoding::convertEncoding
Also fixed encoding check that not only a code point but a string can
also be used as a parameter.
Update phpunit tests and split them out for each class
Normal test page is still combined for all classes but updated to
correctly use each class
