Update flipper and resolve breaking change

[rmtolmach]

Summary

• This work is behind a feature toggle (flipper): NO
• This PR updates the flipper gem (and its dependencies) and resolves the breaking change from the update. In the flipper PR UI: Replace breadcrumbs with configurable nav flippercloud/flipper#853, breadcrumbs were removed, which made the UI break and tests fail (see Bump flipper-ui, flipper, flipper-active_record and flipper-active_support_cache_store #16396 (comment) for details). Shoutout to @ryan-mcneil for writing tests that caught the error 🤜 🤛
• I added a link to our docs. If people don't like this, I'm happy to remove it.
• We lose the Home button, but it sent you to the same page as the Features button, so we're not loosing anything useful.
• One of the nav items flipper was showing by default with the upgrade was Settings. I personally don't think this is worth the nav space, so I've removed it from the navigation. It still exists (https://staging-api.va.gov/flipper/settings), but there's no link to it anywhere. But if this is something we think people will find useful, I can add it back in.
• To reproduce this bug on master, run bundle update flipper, start your rails console and then navigate to http://127.0.0.1:3000/flipper/features. And/or run tests in spec/requests/flipper_request_spec.rb after updating flipper.
• The solution is to incorporate the changes made to lib/flipper/ui/views/layout.erb into our file of the same name.
• I'm on the Platform Product team. The Backend CoP is responsible for updating gems.

Related issue(s)

• Resolve flipper gem breaking change va.gov-team#81501

Testing done

• New code is covered by unit tests - flipper have their own tests.
• Describe what the old behavior was prior to the change - see screenshots and summary sections.
• Describe the steps required to verify your changes are working as expected. Exclusively stating 'Specs run' is NOT acceptable as appropriate testing - I clicked around in the UI locally to make sure the links worked.

Screenshots

Before (w/ breadcrumbs):

After (without breadcrumbs):

What areas of the site does it impact?

The Flipper UI in each env (https://staging-api.va.gov/flipper, for example)

Acceptance criteria

• I fixed|updated|added unit tests and integration tests for each feature (if applicable).
• No error nor warning in the console.
• Documentation has been updated (link to documentation)
• No sensitive information (i.e. PII/credentials/internal URLs/etc.) is captured in logging, hardcoded, or specs
• If app impacted requires authentication, did you login to a local build and verify all authenticated routes work as expected
• I added a screenshot of the developed feature

[RachalCassity]

We might want to update the ul class according to this PR.
Here's the layout file:https://github.com/flippercloud/flipper/blob/966a956f36cd0ef6a838b9ae6b20818c5509766c/lib/flipper/ui/views/layout.erb. Here's what flipper suggests:

      <nav>
        <ul class="nav nav-underline mb-3 align-items-center">
          <% if Flipper::UI.configuration.application_href %>
            <li class="nav-item">
              <a class="nav-link" href="<%= Flipper::UI.configuration.application_href %>">
                ‹ App
              </a>
            </li>
          <% end %>


          <% Flipper::UI.configuration.nav_items.each do |item| %>
            <li class="nav-item">
              <a href="<%= url_for(item[:href]) %>" class="nav-link<%= " active" if request.url.start_with?(url_for(item[:href])) %>">
                <%= item[:title] %>
              </a>
            </li>
          <% end %>

          <li class="nav-item ms-auto text-muted small">
            <a href="https://www.flippercloud.io/docs/ui?utm_source=oss&utm_medium=ui&utm_campaign=docs">Docs</a>
            &bull;
            Version: <%= Flipper::VERSION %>
          </li>
        </ul>
      </nav>

[rmtolmach]

That's what I started with, but I changed it up just a little because I didn't love the way it looked 😆

Notable changes:

• I removed the link to Settings
• I made it an unordered list
• I changed the Docs link to link to our internal docs
• I removed the Version

[ryan-mcneil]

yaaaas