feat: add twiter + download icons to image export modal

Author: Lewis Youl

app/views/modals/snippets/picture.html.erb

@@ -7,7 +7,14 @@
 	</div>
 
 	<div class="flex justify-end mt-4">
-		<%= button_tag('Tweet', class: 'button--cta-tertiary mr-2', data: { action: 'click->picture#tweet' }) %>
-		<%= button_tag('Download', class: 'button--cta-tertiary', data: { action: 'click->picture#download' }) %>
+    <%= button_tag class: 'button--cta-tertiary mr-2', data: { action: 'click->picture#tweet' } do %>
+      <%= render partial: 'shared/icons/twitter', locals: { classes: 'h-5 w-5 mr-1' } %>
+      <span class="font-normal">Tweet</span>
+    <% end %>
+
+    <%= button_tag class: 'button--cta-tertiary', data: { action: 'click->picture#download' } do %>
+      <%= render partial: 'shared/icons/download', locals: { classes: 'h-5 w-5 mr-1' } %>
+      <span class="font-normal">Download</span>
+    <% end %>
 	</div>
 </div>

app/views/shared/icons/_download.html.erb

@@ -0,0 +1,3 @@
+<svg class="<%= classes %>" fill="currentColor" viewBox="0 0 20 20" xmlns="http://www.w3.org/2000/svg">
+  <path fill-rule="evenodd" d="M3 17a1 1 0 011-1h12a1 1 0 110 2H4a1 1 0 01-1-1zm3.293-7.707a1 1 0 011.414 0L9 10.586V3a1 1 0 112 0v7.586l1.293-1.293a1 1 0 111.414 1.414l-3 3a1 1 0 01-1.414 0l-3-3a1 1 0 010-1.414z" clip-rule="evenodd"></path>
+</svg>