VSA allow users to toggle aggregated data backend

What does this MR do and why?

Describe in detail what your merge request does and why.

As part of #344803 (closed) this MR adds a toggle to the group VSA page allowing user's to opt into the new 'aggregated data' backend that will soon be defaulted on. In the meantime user's can opt in and out to take a look at the new backend.

When the Toggle is clicked toast message is displayed with the updated status, then the page is refreshed with the toggle in the new state.

Depends on !82389 (merged)

Screenshots or screen recordings

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Feature flag enabled

With the use_vsa_aggregated_tables feature flag

Tooltip	Toggle behaviour
Screen_Recording_2022-03-09_at_7.55.55_pm	vsa-aggregated-toggle-720

Feature flag disabled

How to set up and validate locally

1. Enable the use_vsa_aggregated_tables feature flag, open the rails console with rails c and execute the Feature.enable

Feature.enable(:use_vsa_aggregated_tables)

1. Apply the diff in !82481 (comment 873438957)
2. Ensure you have an EE license, or stub the cycle_analytics_for_groups license feature to true
3. Create a group
4. (optional) Create a project within the group (make sure to initialize the project with a readme, or create it from a template)
5. Navigate to value stream analytics for the group, ie for a group name new-vsa-group it would be http://<gdk>/group/new-vsa-group/-/analytics/value_stream_analytics (or you can navigate from the left menu)

MR acceptance checklist

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• I have evaluated the MR acceptance checklist for this MR.

Related to #352428 (closed)