replace slippers with django-cotton

main reason: slippers cannot pass request via context inside its
components, making it annoying to use template takes that take request.
more reasons: not actively worked on, no named slots, having to define
components in components.yaml + new components do not get registered
without restarting server

games/templates/cotton/popover.html

@@ -0,0 +1,7 @@
+<div data-popover
+     id="{{ id }}"
+     role="tooltip"
+     class="absolute z-10 invisible inline-block text-sm text-white transition-opacity duration-300 bg-white border border-purple-200 rounded-lg shadow-sm opacity-0 dark:text-white dark:border-purple-600 dark:bg-purple-800">
+    <div class="px-3 py-2">{{ slot }}</div>
+    <div data-popper-arrow></div>
+</div>