Searching for users from LDAP

Dropdowns

Users from LDAP can be selected in user dropdowns.

Closes #365 (closed)

Related to #249 (closed)

Button to add user from LDAP in management panel

(Previously part of !713 (closed))

Added a button to create a new user:

This opens a new modal, where you can search for users. After users are retrieved, their name, email and affiliation are shown:

A user can be created on ProjectForum by clicking on their name:

Already existing users are not created again. If that is the case, this is silently handled and no error is shown to the user, a new user is not created.

Admins can also click on the "Created" label in order to go directly to the user page.

Closes #377 (closed)