Allow to search role by group or entity which created it

[asvishnyakov]

Problem: We need the way to get only roles created by storefront

Solution: Use CreatedBy = "frontend"

Alternative (optional): Use Group field

Proposal of changes: Inherit Role class from AuditableEntity, add Group field, extend RoleSearchRequest with Group, CreatedBy fields

[asvishnyakov]

@tatarincev Any plans?