Fix CSS specificity issue with easymde's css

PR go-gitea#18069 introduced a regression in certain overwritten editor styles
because the dynamic loading of easymde.min.css causes its's style to
apply after our supposed override styles.

Solve this by bundling the styles into index.css. We should later aim to
completely replace easymde.min.css completely with our own styles so there
are no more conflicts.

web_src/js/features/comp/EasyMDE.js

@@ -25,10 +25,10 @@ export async function importEasyMDE() {
   // https://github.com/codemirror/CodeMirror/issues/5484
   // https://github.com/codemirror/CodeMirror/issues/4838
 
+  // easymde's css is loaded via webpack config
   const [{default: EasyMDE}, {default: CodeMirror}] = await Promise.all([
     import(/* webpackChunkName: "easymde" */'easymde'),
     import(/* webpackChunkName: "codemirror" */'codemirror'),
-    import(/* webpackChunkName: "easymde" */'easymde/dist/easymde.min.css'),
   ]);
 
   // CodeMirror plugins must be loaded by a "Plain browser env"

webpack.config.js

@@ -46,6 +46,7 @@ export default {
       resolve(__dirname, 'web_src/js/jquery.js'),
       resolve(__dirname, 'web_src/fomantic/build/semantic.js'),
       resolve(__dirname, 'web_src/js/index.js'),
+      resolve(__dirname, 'node_modules/easymde/dist/easymde.min.css'),
       resolve(__dirname, 'web_src/fomantic/build/semantic.css'),
       resolve(__dirname, 'web_src/less/misc.css'),
       resolve(__dirname, 'web_src/less/index.less'),