Move fomantic and jQuery to main webpack bundle (#11997)

This saves around 3 MB binary size by not including useless fomantic
files in the build. Also, this allows us to move jQuery into the main
bundle as well which eliminates a few HTTP requests.

Also included are webpack config changes:

- split less and css loaders to speed up compliation
- enable css sourcemaps
- switch css minfier plugin to cssnano-webpack-plugin which works better
  for sourcemaps than the previous plugin

Co-authored-by: techknowlogick <techknowlogick@gitea.io>

package.json

@@ -15,7 +15,7 @@
     "clipboard": "2.0.6",
     "core-js": "3.6.5",
     "css-loader": "3.5.3",
-    "cssnano": "4.1.10",
+    "cssnano-webpack-plugin": "1.0.3",
     "domino": "2.1.5",
     "dropzone": "5.7.1",
     "fast-glob": "3.2.2",
@@ -29,10 +29,8 @@
     "mini-css-extract-plugin": "0.9.0",
     "monaco-editor": "0.20.0",
     "monaco-editor-webpack-plugin": "1.9.0",
-    "optimize-css-assets-webpack-plugin": "5.0.3",
     "postcss-loader": "3.0.0",
     "postcss-preset-env": "6.7.0",
-    "postcss-safe-parser": "4.0.2",
     "svg-sprite-loader": "5.0.0",
     "svgo": "1.3.2",
     "svgo-loader": "2.2.1",