logic: reimplemented task system to abort ast visiting

* reimplemented interrupting TaskParseCxx by adding a listener for the MessageInterruptTask and returning a failure status code on update. This cancels the parent sequence task which results in the indexed items not getting inserted into the persistent storage
* removed the capability for interrupting from TaskScheduler
* changed task system to be closer to the standard behavior tree implementation
* changed task system to accommodate the 3 status return types: Running, Success and Failure
* made TaskGroupSequential fail once a member task fails
* made TaskGroupParallel fail once a member task fails
* split TaskParse... into one task for indexing and one task for injecting
* added TaskRunner that handles updating and resetting the managed task
* fixed numbers that are shown as parsed file count in indexing ui
* fixed deadlock that originated from interaction between TaskScheduler and MessageQueue (one thread wanted to destroy a message listener on a task while the other one wanted to send as message as a task)

src/lib/data/TaskCleanStorage.cpp

@@ -12,33 +12,25 @@ TaskCleanStorage::TaskCleanStorage(
 {
 }
 
-void TaskCleanStorage::enter()
+void TaskCleanStorage::doEnter()
 {
 	m_dialogView->showProgressDialog("Clearing Files", std::to_string(m_filePaths.size()) + " Files");
 }
 
-Task::TaskState TaskCleanStorage::update()
+Task::TaskState TaskCleanStorage::doUpdate()
 {
 	m_storage->clearFileElements(m_filePaths);
 
 	m_filePaths.clear();
 
-	return Task::STATE_FINISHED;
+	return STATE_SUCCESS;
 }
 
-void TaskCleanStorage::exit()
+void TaskCleanStorage::doExit()
 {
 	m_dialogView->hideProgressDialog();
 }
 
-void TaskCleanStorage::interrupt()
-{
-}
-
-void TaskCleanStorage::revert()
-{
-}
-
-void TaskCleanStorage::abort()
+void TaskCleanStorage::doReset()
 {
 }