Validations for the Input's fields

I am developing a custom input plugin in which I have added a TextField to take Source Ip as in Input.

I would like to validate the entered IP to be valid in IPv4/IPv6 format.

In my case, I do not want to change the Graylog server code instead I would like to indicate inside the Plugin to validate for a particular format. This extension is not available in the current graylog code.

It would be really good to add validations for IP address which might be very useful for many people.

## Expected Behavior
Entered IP address in the text field should be validated against the standard IPv4/IPv6 format.

## Current Behavior
No validation present for the text field to add validation for IP address.

## Possible Solution

## Steps to Reproduce (for bugs)
1. Add new TextField to take an IP address as an input in an Input Plugin.
2. Enter any content which doesn't match the IP address in the field and Save the input configuration.

## Context
Now the input is saved without any errors. However at the backend when tried to perform some operation this will fail.

So it is a really good idea and it would be logical to have an IP validation for Inputs.