Add go licenses to licenses.txt (#21034)

`make go-licenses` will generate `assets/go-licenses.json` which is then included in the webpack build. 

This step depends on both go and node being present, so unfortunately, I could not automate the generation by hooking it up to `tidy` as that target is triggered on CI where we do not have a docker image with both go an node.

It should be ran from time to time, ideally after each go mod update.

build/generate-go-licenses.js

@@ -0,0 +1,30 @@
+#!/usr/bin/env node
+import fastGlob from 'fast-glob';
+import {fileURLToPath} from 'url';
+import {readFileSync, writeFileSync} from 'fs';
+import wrapAnsi from 'wrap-ansi';
+import {join, dirname} from 'path';
+
+const base = process.argv[2];
+const out = process.argv[3];
+
+function exit(err) {
+  if (err) console.error(err);
+  process.exit(err ? 1 : 0);
+}
+
+async function main() {
+  const data = fastGlob.sync('**/*', {
+    cwd: fileURLToPath(new URL(`../${base}`, import.meta.url)),
+  }).filter((path) => {
+    return /\/((UN)?LICEN(S|C)E|COPYING|NOTICE)/i.test(path);
+  }).sort().map((path) => {
+    return {
+      name: dirname(path),
+      body: wrapAnsi(readFileSync(join(base, path), 'utf8') || '', 80)
+    };
+  });
+  writeFileSync(out, JSON.stringify(data, null, 2));
+}
+
+main().then(exit).catch(exit);