[FEATURE] Support multi datasources in the "Tenants" tab

[derek-ho]

Is your feature request related to a problem?
Support multiple datasources functionality in the "Tenants" tab. This would involve some complications, since tenancy has some hooks into localstorage/sessionstorage. We would need to make sure any hooks to these stores are handled properly across datasources, such as by adding a prefix to to the key that is stored/retrieved or removing its usage where appropriate.

Acceptance criteria

• Data source picker shared component is present on the page with a sensible UX
• Data source selections that should be persisted across tabs is accurately persisted
• Selected datasource prior to landing on this page is correctly populated (if applicable), and defaults are selected if not applicable
• "Manage" sub tab is appropriately handling multiple datasources
• Links to any dashboards/visualizaitons is correctly handling multiple datasources as well
• "Configure" sub tab is appropriately handling multiple datasources
• Bring in modals where appropriate to confirm/bubble up datasource information to the user

OPEN QUESTIONS

What solution would you like?
Support multiple datasources in the "Tenants" tab.

What alternatives have you considered?
None

Do you have any additional context?
Depends on #1795 to have data source picker available.

[derek-ho]

[Triage] This is part of the meta of supporting multi datasources in the security plugin.

[derek-ho]

Adding some context that came up - since we are moving away from tenancy the cluster selector on this page may be marked as "read only" with "Local Cluster" selected with no way of selecting another cluster. Users may have to log into the other cluster to touch tenancy information, since the concept might get confusing especially with datasources themselves being specific to tenants within the local cluster.

[derek-ho]

Merged into feature branch