Support multiple DHCP ranges from UI

[cotosso]

Brief description

• The UI is currently designed to manage only one DHCP range per interface.
• It is possible to manually add additional DHCP ranges at configuration level (outside the UI).
• However, when multiple DHCP ranges exist, the UI behaves inconsistently, so it will be very useful to support this feature also directly from the UI.

Current behavior and issues

• Card view:
  The card always displays the first DHCP range, which is correct and expected.

• Edit view:
  The UI loads and edits the last DHCP range found in the configuration file, regardless of naming or logical order.
  Example: if the configuration contains:

  config dhcp 'lan'
  .
  .
  config dhcp 'lan_3'
  .
  .
  config dhcp 'lan_2'
  .
  .
  

(in this order), the edit form will always show and modify dhcp 'lan_2'.

• Edit behavior:
  The modification is internally consistent (the range shown is the one modified), but it is not the same range displayed in the card view.

• Other DHCP ranges:
  All other DHCP ranges remain unchanged.

Problem

This creates a UI inconsistency and configuration ambiguity:

• The user sees one DHCP range in the overview card.
• The user edits a different DHCP range in the edit form.
• This can lead to misconfiguration without any visible warning.

Expected behavior / fix proposal

I propose to allow managing multiple DHCP ranges natively from the UI, providing the ability to define mutiple ranges.
As a suggestion we could use the same logic and components used for the DHCP options:

This way we can easily manage the ability to add and remove ranges, leaving only the first range as mandatory.

Version : NethSecurity 8.7.1