add ability for users to provide feedback directly from Matomo for WordPress

[diosmosis]

It is believed that users of Matomo for WordPress are less likely to complain or provide feedback when something goes wrong or if something they need is missing. To overcome this it might help to make providing feedback as simple as possible.

Instead of links to the forum, a dedicated feedback form that users can use to quickly send a message might provide useful feedback.

The form could send an email at first, though some WordPress installs might not be set up to send emails.