Marking tasks as internal

[blackandred]

An internal task is a task that is not listed when typing a rkd :tasks command. There should be a switch to show all tasks, including internal ones - rkd :tasks --all

Reasons for hiding a task:

• Task can be strictly technical, as a part of bigger automation
• Task could be designed to be a part of pipeline, the user should run only the pipeline

How to hide a task:

• Define a property is_internal = True, or a property method on TaskInterface implementation
• Declare a task using TaskDeclaration(TaskInterface, internal=True) to override TaskInterface setting

[blackandred]

Implemented, watiing for review.