[INTERNAL] TaskRepository: Remove #addTask API

Custom tasks shall now be provided as extensions in the ProjectGraph

lib/tasks/taskRepository.js

@@ -44,22 +44,11 @@ function getTask(taskName) {
 	}
 }
 
-function addTask({name, specVersion, taskPath}) {
-	if (taskInfos[name]) {
-		throw new Error(`taskRepository: A task with the name ${name} has already been registered`);
-	}
-	taskInfos[name] = {
-		path: taskPath,
-		specVersion
-	};
-}
-
 function getAllTaskNames() {
 	return Object.keys(taskInfos);
 }
 
 module.exports = {
 	getTask,
-	addTask,
 	getAllTaskNames
 };