As a user, I want to be able to archive a Plan from the MTV UI, in order to stay in the MTV UI for all migration related operations.

A plan can be archived at any stage, but running. If a plan is running, it must be cancelled before being archived, so that all assets / dependencies are at rest.

When a plan is archived, the only available options are "Clone to new plan" (see MTV-109) and "Delete".

We want to consider moving archived plans out of the main plan view, to avoid cluttering it with not actionable items.