Mobile view

[gabehamilton]

When the resource directory is viewed on a screen less than MOBILE_SIZE switch to a mobile view.

In the mobile view:

• Side menu and tabs become standalone landing pages.
  • alternative 1: move into a top-left dropdown menu
  • alternative 2: move into an accordion widget - tabs would be links to pages.
• Create button goes to standalone create page instead of Modal.

Note: current sidebar stacks with content at 750px or less. This Issue depends on the decisions made in https://github.com/near/ai-platform/issues/41

### Tasks
- [ ] Problem: only 2 tabs show on mobile