Multiple Opensearch Dashboards instances support multi-tenant feature

[xikunyu]

Is your feature request related to a problem? Please describe.
I tried to deploy multiple opensearch-dashboards instances. It worked and I can successfully login into the second dashboards webui, but when I tried to switch to specific tenant, it can't display any existed dashboard or index pattern of the tenant.

Describe the solution you'd like
I could switch to any tenant in the second dashboards.

[peternied]

While this mentions the tenants feature from the security plugin - it seems like workspaces might be a better fit.

[joshuarrrr]

@Flyingliuhub @tianleh - Do you have any insight or context to provide here?