[Feature Request] notEqualTo should include name of control

[lonix1]

Similar to #12

Let's say we define a "password" validation like this:

password: ["", [Validators.required, CustomValidators.notEqualTo(email)]],

The notEqualTo validator's metadata includes the invalid value, so we can show this message:

'password' cannot equal '[email protected]'

But, this is not informative. It should include the name of the target control (email), so that we can do this instead:

'password' cannot equal 'email'

That makes more sense.

So passwordControl.errors should return: { control: {}, otherControlName: 'email' }

[rsaenen]

What's the goal?

To use the control name with a translation and display it to the user?

[lonix1]

Yes, so you can use this:

'password' cannot equal 'email'

Otherwise you don't know which control (i.e. email) it equalled.