[FIX]Fix deprecated warnings for preg_match() and mb_strtolower() in Webmail sieve filters

[Baraka24]

While running: php console.php sieve:filters in Tiki see handle the filtering in Tiki , we are getting:

$ php console.php sieve:filters

Undefined variable $tikiroot on line 16 of C:\Apache24\htdocs\tiki1\tiki\lib\cypht\integration\classes.php preg_match(): Passing null to parameter #2 ($subject) of type string is deprecated on line 179 of C:\Apache24\ht docs\tiki1\tiki\vendor_bundled\vendor\jason-munro\cypht\lib\request.php mb_strtolower(): Passing null to parameter #1 ($string) of type string is deprecated on line 194 of C:\Apache24\ htdocs\tiki1\tiki\vendor_bundled\vendor\jason-munro\cypht\lib\module.php

• The first issue has been resolved in Merge request