Bundle CSS with Hugo's Sass feature (#705)

* migrate bootstrap and flags to bundle

* migrated main.css

* migrate navbar.css and plyr

* migrated mulish font and darkreader

* migrated static/css/sections stylesheets

* migrated list page and sidebar styles

* migrated search.html ( nothing to add )

* migration single page styles

* remove duplicated style tags

* migrate notes.  Deleted unused css in static

* migrate 404 css to bundle

* migrate katex styles

* migrate embedpdf styles

* migrated katex css

---------

Co-authored-by: Aaron Qian <aaron@yeet.io>

data/toha/styles.yml

@@ -0,0 +1,31 @@
+flags:
+  styles:
+    - flag-icon-css/css/flag-icons
+
+videoplayer:
+  services:
+    plyr:
+      styles:
+      - plyr/dist/plyr
+
+darkmode:
+  services:
+    darkreader:
+      styles:
+      - ./colortheme/colortheme
+
+syntaxhighlight:
+  services:
+    hljs:
+      styles:
+      - highlight.js/scss/atom-one-dark
+
+math:
+  services:
+    katex:
+      styles:
+      - katex/dist/katex
+
+embedpdf:
+  styles:
+  - ./sections/pdf-viewer