feat(kanban): use total task count from the api instead of manually calculating it per bucket

This fixes an ux issue where the total count would show a wrong number of total tasks because that was the number of tasks which were loaded at the time. In combination with bucket limits, this caused error messages when the user would attempt to drag tasks into a bucket which appeared not full but was.

src/modelTypes/IBucket.ts

@@ -10,6 +10,7 @@ export interface IBucket extends IAbstract {
 	tasks: ITask[]
 	isDoneBucket: boolean
 	position: number
+	count: number
 	
 	createdBy: IUser
 	created: Date