Implement real time validation

[Siegrift]

As discussed in https://api3workspace.slack.com/archives/C020RCCC3EJ/p1624207461017900

The validation is triggered when the form is submitted (action is pressed), but we should probably validate real time for better UX. Sometimes it is easy to do, but sometimes not (I think we do some async validation as well).

[Siegrift]

Another stretch to this validation is the following case:

1. Open delegation modal (assuming you are able to delegate)
2. You type the address and (possibly realtime) validation passes
3. The address delegates in the meantime and you press a button
4. The transaction would revert (because the address already has a delegate)...

Similar cases can happen for other things, the point is, that we should check whether the action is possible before crating the transaction, because blockchain state can change in the meantime...

However, this will happen very rarely.

[bbenligiray]

Promoting products and services in issues is not welcome

[bbenligiray]

I'm not sure that this is typical or needed