[ZBXNEXT-8503] Allow regex in SAML group pattern to use for group and role mapping

When configuring SAML you can use the SAML group pattern to match SAML Groups to Zabbix Groups and Zabbix Roles. Let’s say you have 2 Zabbix Roles (admin + user) and 4 Zabbix Groups (allowing access to different host groups) then you have to create 2 x 4 = 8 different SAML Groups + group mappings.

It would be more easy to use regex and regex groups in the SAML group pattern field. Thus you could handle the 8 group mappings in just one rule, e.g.:

SAML group pattern: zabbix-grp_(.)-role_(.)
User groups: Group-\1
User role: Role-\2

\1 and \2 should be references to the regex group in SAML group pattern.