Add unique ID to the form block

[rodica-andronache]

What problem does this address?

Suggested by this user https://secure.helpscout.net/conversation/2967244663/466317

He needs the form to have a unique ID, to set up some specific tracking.

For the moment, we have a unique ID, but that is added to the <div> element that is before the <form> tag.

What is your proposed solution?

Have a unique ID to the <form> tag

Will this feature require documentation? (Optional)

None