Services: DHCP: Leases (4+6): migrate to MVC

[fichtner]

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• I have read the contributing guide lines at https://github.com/opnsense/core/blob/master/CONTRIBUTING.md
• I am convinced that my issue is new after having checked both open and closed issues at https://github.com/opnsense/core/issues?q=is%3Aissue

Is your feature request related to a problem? Please describe.

Static pages need to be removed eventually. Services page offers opportunity for it and enables API handling of the functionality.

Describe the solution you like

Likely easy to migrate using the searchRecordsetBase() method.

Describe alternatives you considered

N/A

Additional context

N/A

[swhite2]

DHCPv4: 4b7a1ce
DHCPv6: f782be9