References panel: Serve cached data instead of refetching

Created by: umpox

We should cache loaded panel data against a revision to improve performance

1. Go to https://sourcegraph.com/github.com/sourcegraph/sourcegraph/-/blob/client/wildcard/src/components/Button/Button.tsx?L47:14#tab=references
2. Click between 'references', 'history' and 'definition' tabs
3. Notice how we refetch data every time. This issue is compounded for widely used references

This data is unlikely to change for the current revision, so we should cache it for as long as the user is on the page against this revision.

This also fixes a potential (?) bug where symbol data could be out-of-sync with the loaded file blob. As symbol data could refetch from latest main without reloading the blob content