Display tokens staked chart on Astar portal

[bobo-k2]

Motivation It would be very useful to have historical information about staked amounts on the portal dashboard page. This is the third ticket in series of tickets related to adding total staked ASTR/SDN on the dashboard page. Depends on #754

Suggested Solution Add a new chart to Astar portal dashboard page to display tokens staked chart. See existing dashboard charts for guidelines.

Alternatives Not at the moment. Any ideas are welcome.

Additional Information Please comment if the ticket is not clear enough.