improved duration and minute selector (#2264)

* do not close modal if form is dirty
* deprecated TimesheetConfiguration
* inject timezone in form types
* cleanup usage of UserDateTimeFactory
* allow to configure increment steps for minutes
* use 15 minutes step for datetimepicker in project edit form
* use rounding rules for increments in minute select for begin and end
* allow duration in multi user and admin timesheet forms
* make dropdown values configurable

tests/DependencyInjection/ConfigurationTest.php

@@ -286,6 +286,8 @@ class ConfigurationTest extends TestCase
                     'lockdown_period_end' => null,
                     'lockdown_grace_period' => null,
                 ],
+                'duration_increment' => null,
+                'time_increment' => null,
             ],
             'user' => [
                 'registration' => true,