General Desciption:
Fix and enhancements for Mapping Source fields validations

Detailed Description:
This patch adds proper validation during creation of a mapping source and several formatting rules
to prevent errors/wrong input when specifying Active Directory connection parameters.
--- Username should now be in "username@my.company.domain" format
--- Active Directory path should now be in proper ActiveDirectory path format (e.g.
CN=Users,DC=my,DC=company,DC=domain, etc.)
--- Port will only accept numeric values