[labels view] When a label is selected, the main time series panel should display the series corresponding to the label values

[grafakus]

Feature description

For instance, if the grafana_version label is selected, the main timeseries should display 3 series (one for each version):

Which will help the user to keep the context.

Alternatives considered

Describe alternatives you've considered

We could add a "Single" button like Explore Logs has to switch from one vizualisation to the other:

But the "Labels" view already has a timeseries at the top of the screen.

Additional context

We should be careful that this change should work in these use cases:

1. When landing on the page, after selecting a label (common case)
2. Coming from a favorited vizualisation that has a groupBy value
3. When landing from a shared link that has a groupBy value
4. When more than 10 series are available, the header actions of the main timeseries should include the "Expand panel" button and clicking on this button should open the drawer with all the series

Note also that the colors used on the series should always match the colors of the panels below