Allow Forward Rules Between the Same Zone or Any Zone

[cotosso]

Description:
In the current implementation of the forward rules, it is not possible to create rules where the source and destination are within the same zone, a specific zone, or the "any" option. This limitation results in several practical issues and inefficiencies.

Examples:

• Rules Between Two LAN Zones:

It is currently impossible to create a rule using two LAN zones. For instance, if I have multiple LAN interfaces (each with its own CIDR), I am forced to specify one zone as LAN and the other as ANY.

• Rules Using "Any" for Both Source and Destination:

If I want to block all traffic between zones and allow specific traffic only on certain ports using host sets, I am required to create multiple rules instead of a single, comprehensive rule.
On NethSecurity 8, the "any" option operates only within the forward context. As a result, it cannot block access to the firewall itself.

Proposed Solution:
Relax form validator to:

• Allow the creation of forward rules where the source and destination are the same zone.
• Enable the use of the "any" option for both source and destination in forward rules.