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>

templates/base/footer.tmpl

@@ -11,8 +11,6 @@
 	{{template "custom/body_outer_post" .}}
 
 	{{template "base/footer_content" .}}
-
-	<script src="{{StaticUrlPrefix}}/js/jquery.js?v={{MD5 AppVer}}"></script>
 {{if .RequireSimpleMDE}}
 	<script src="{{StaticUrlPrefix}}/vendor/plugins/simplemde/simplemde.min.js"></script>
 	<script src="{{StaticUrlPrefix}}/vendor/plugins/codemirror/addon/mode/loadmode.js"></script>
@@ -23,9 +21,6 @@
 {{end}}
 
 <!-- Third-party libraries -->
-{{if .RequireMinicolors}}
-	<script src="{{StaticUrlPrefix}}/vendor/plugins/jquery.minicolors/jquery.minicolors.min.js"></script>
-{{end}}
 {{if .RequireU2F}}
 	<script src="{{StaticUrlPrefix}}/vendor/plugins/u2f/index.js"></script>
 {{end}}
@@ -34,8 +29,10 @@
 		<script src='{{ URLJoin .RecaptchaURL "api.js"}}' async></script>
 	{{end}}
 {{end}}
-	<script src="{{StaticUrlPrefix}}/fomantic/semantic.min.js?v={{MD5 AppVer}}"></script>
 	<script src="{{StaticUrlPrefix}}/js/index.js?v={{MD5 AppVer}}"></script>
+{{if .RequireMinicolors}}
+	<script src="{{StaticUrlPrefix}}/vendor/plugins/jquery.minicolors/jquery.minicolors.min.js"></script>
+{{end}}
 {{template "custom/footer" .}}
 </body>
 </html>

templates/base/head.tmpl

@@ -95,7 +95,6 @@
 {{if .RequireSimpleMDE}}
 	<link rel="stylesheet" href="{{StaticUrlPrefix}}/vendor/plugins/simplemde/simplemde.min.css">
 {{end}}
-	<link rel="stylesheet" href="{{StaticUrlPrefix}}/fomantic/semantic.min.css?v={{MD5 AppVer}}">
 	<link rel="stylesheet" href="{{StaticUrlPrefix}}/css/index.css?v={{MD5 AppVer}}">
 	<noscript>
 		<style>