Filter strategies by blockchain

[kenkunz]

Goal

As an investor viewing strategies on the homepage or strategy index page, I want to filter strategies by blockchain, so that I can view the strategies I'm most interested in.

Acceptance criteria

1. A new blockchain filter selector is available on the homepage and strategies index page
2. The filter includes all of the chains that are associated with at least 1 strategy that the user has access to view (admin users can access unpublished strategies)
3. The filter includes an "all" option, which is the default
4. When clicking a chain filter option, the list of displayed strategies updates to show only the matching strategies
5. On the strategies index page, the selected filter is added to the URL as a param; clicking away and "back" preserves the selected filter
6. For admin users, the blockchain and status (live vs. unpublished) filters may be combined (as "AND" criteria – only strategies are displayed that meet both filters)
7. If no strategies meet the selected criteria, an appropriate fallback message is displayed