Add "Task" to the end of the command palette options

[Masstronaut]

Typing "Create task" finds no results in the command palette search, because "Tasks:" appears at the start of the item:

To support both tasks create and create task would be trivial: add "task" to the end of the command palette options. The same applies to editing and toggling tasks because both commands lack the term "task" at the end:

This could be resolved by changing the command names as follows (and while we're at it fix the capitalization of Done):
Tasks: Toggle Done -> Tasks: Toggle done task
Tasks: Create or edit -> Tasks: Create or edit task

[Masstronaut]

Implemented in #186