move swagger-ui to webpack/npm (#9714)

Created a second webpack output file for swagger-ui which is loaded on
the /api/swagger route. One notable difference is the absence of the
swagger favicon that was previously used which is now the gitea icon. I
see no easy way to restore that favicon, so I decided to not keep it.

web_src/js/swagger.js

@@ -0,0 +1,30 @@
+import SwaggerUI from 'swagger-ui';
+import 'swagger-ui/dist/swagger-ui.css';
+
+window.addEventListener('load', async () => {
+  const url = document.getElementById('swagger-ui').dataset.source;
+  const res = await fetch(url);
+  const spec = await res.json();
+
+  // Make the page's protocol be at the top of the schemes list
+  const proto = window.location.protocol.slice(0, -1);
+  spec.schemes.sort((a, b) => {
+    if (a === proto) return -1;
+    if (b === proto) return 1;
+    return 0;
+  });
+
+  const ui = SwaggerUI({
+    spec,
+    dom_id: '#swagger-ui',
+    deepLinking: true,
+    presets: [
+      SwaggerUI.presets.apis
+    ],
+    plugins: [
+      SwaggerUI.plugins.DownloadUrl
+    ]
+  });
+
+  window.ui = ui;
+});