feat(dhcp): support multiple dhcp ranges

[m-dilorenzi]

This pull request refactors the DHCP interface handling to support multiple DHCP ranges per network interface in set and get interfaces APIs, ensuring better flexibility and correctness in DHCP configuration.

• updated the data structure for interfaces to use a ranges array instead of single first and last fields, allowing each interface to have multiple DHCP ranges. This affects how interfaces are listed, edited, and retrieved
• added validation to ensure each range is within the interface's subnet, the IPs are non-empty, and the last IP is greater than the first
• edit logic now deletes existing DHCP configs for the interface and creates new sections for each range
• the get-interface API (used to retrieve interface details for editing) now includes class_start_ip and class_end_ip fields to indicate the valid IP range for UI input box check

Closes: #1448