Fix and cleanup of LocalTaskInterface

1. +++ b/translators/tmgmt_local/includes/tmgmt_local.pages.inc
   @@ -230,7 +230,7 @@ function tmgmt_local_translation_form_save_as_completed_submit($form, FormStateI
      }
      if ($all_done) {
   -    $task->setStatus(TMGMT_LOCAL_TASK_STATUS_COMPLETED);
   +    $task->setStatus(LocalTask::STATUS_COMPLETED);
   

   why not use the interface here and elswhere?

2. +++ b/translators/tmgmt_local/src/Entity/LocalTask.php
   @@ -462,19 +389,30 @@ class LocalTask extends ContentEntityBase implements EntityChangedInterface, Ent
   +   */
   +  public static function getStatuses() {
   +    return $statuses = array(
   

   $statuses doesn't do anything here.

3. +++ b/translators/tmgmt_local/tmgmt_local.module
   @@ -395,22 +370,6 @@ function tmgmt_local_task_statistic(LocalTask $task, $key) {
   - * @return array
   - *   A list of all available statuses.
   - */
   -function tmgmt_local_task_statuses() {
   

   Note that we are in beta now. Which means that strictly speaking, we are not allowed to do API changes anymore, as someone else might rely on this.

   I think local translator is still fresh enough so that this isn't a big issue. But in future, please keep old functions and instead mark them as @deprecated. See how core does it.

I think we discussed that local translator is an early port and is more in an experimental state.
We went through the local translator and it's clear that it is not yet cleanly converted and missing interfaces at all. Constants are for instance still as define() instead of added to the interface.

I wouldn't like to see the cleanup being limited by the beta discussion and vote for unlimited cleanup in local translator.

Discussed point 1.

Thanks, committed.