Allow to change "Commit address" on email page, not on main page
Since gitlab-ce#23986, the email settings page shows a "Commit address". However, it does not allow to change it. To change it, I need to visit the main settings page and use the dropdown there.
It's very unintuitive that the "emails" page shows me which email address is the "Commit address", and lets me add email addresses, but does not allow me to change the "Commit address". I have to do that on the main settings page, in a dropdown.
According to the "Direct manipulation" principle of UIs, if the "Commit address" is displayed on the email page, it should also be possible to change it there.