[FEATURE] Create a ucx catalog via a cli-command

[JCZuurmond]

Add a cli command create-ucx-catalog to create a catalog called ucx that is available (for read and write) to all workspaces

[asnare]

This also needs to be part of the assign-metastore command. The idea is that we want this (and #2572) to happen as soon as possible once a metastore has been attached, and the assign-metastore command is the most convenient place to ensure that this happens.

Currently some customers will be (externally) assigning the metastore, so as part of this we will need to:

• Update the assign-metastore command to ensure that it's a no-op if a metastore has already been assigned to the workspace (or all in the collection).
• Update the documentation to mention that this is a mandatory step in the migration.

[asnare]

Another requirement, given the metastore can be shared across multiple workspaces is that the catalog may already exist: this is anticipated, and shouldn't be an error.