Display empty screen in readonly mode on dashboards when user without access permissions tries to view it

[bhavyarm]

Describe the feature: There is awesome PR which went into 7.6.0 release thanks to @majagrubic - #54073

Can we get the same behaviour implemented if a user logs in and tries to view dashboards built on index on which she doesn't have any access privileges.

Describe a specific use case for the feature:
Steps to reproduce:

1. Create a space_a and install all sample data dashboards
2. Create a role called spacey and give access permissions to only sample_ecommerce data and all access to space_a using roles page
3. Create an user and assign her spacey role
4. Login with that user
5. Logs and flights dashboard display different error messages per panel.

[elasticmachine]

Pinging @elastic/kibana-app (Team:KibanaApp)

[timroes]

@bhavyarm Unfortunately we cannot do this. We must distinguish here between permissions to view something in Kibana, which we have well under our control and can make sure that we act accordingly like showing a helpful hint, and permissions missing in Elasticsearch. We cannot really react on the later, since most APIs won't tell us that there is a permission issue, but basically just return us no data (which makes sense, since otherwise we would leak information which indexes might exist to a user without permission). So basically everything we can do, is improve the error messages for missing data in a couple of embeddables (Vega will be a bit harder I think, since the user is in control of the request there, but the others might be possible).

I believe improving of those error messages is already tracked via #33161 and #25313