Change donations to contrbutions, add tabbed nav

Introduces components for tabbed navigation and adds a tab menu and item
for non-financial contributions to the donations/contributions page.

app/components/main_with_tabnav_component.html.erb

@@ -0,0 +1,14 @@
+<main class="w-full max-w-6xl mx-auto pb-12 px-4 md:px-6 lg:px-8">
+  <div class="bg-white rounded-lg shadow">
+    <div class="px-6 sm:px-12 pt-2 sm:pt-4">
+      <div class="border-b border-gray-200">
+        <nav class="-mb-px flex" aria-label="Tabs">
+          <%= render partial: @tabnav_partial %>
+        </nav>
+      </div>
+    </div>
+    <div class="px-6 sm:px-12 py-8 sm:py-12">
+      <%= content %>
+    </div>
+  </div>
+</main>