Extract PMA_getUserGroupCount helper function

Signed-off-by: J.M <me@mynetx.net>
Rename local variables in PMA_getTableBodyForUserRightsTable function
(no camel-case in variable names)

Signed-off-by: J.M <me@mynetx.net>
Hide Edit user group link when no groups defined

Signed-off-by: J.M <me@mynetx.net>
Fix server privileges Action colspan (usergroups)

Signed-off-by: J.M <me@mynetx.net>
Add ChangeLog entry for bug #4205
Fix #4205 Add user shows "edit user group" link