Virtual IP MVC/API conversion

[fichtner]

Important notices

Before you add a new report, we ask you kindly to acknowledge the following:

• 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.

Currently interface configuration cannot be automated, also because interface configuration is a complex topic with thousands of lines of code.

Describe the solution you like

To allow for some amount of flexibility with an API the VIPs provide an easy entry for this type of functionality. While here also take care of the Interfaces: Virtual IPs: Status page.

Describe alternatives you considered

See problem description.