Drop fomantic build (#33845)

We would never update or build fomantic again, we have forked it as a
private library long time ago.

So just put the JS and CSS files in "fomantic/build" into git. And use
"import" to use them.

Remove "form.js", rewrite "tab" component.

All source code is from official Fomantic UI build. Will apply patches
in separate PRs.

.dockerignore

@@ -79,18 +79,7 @@ cpu.out
 /public/assets/fonts
 /public/assets/img/avatar
 /vendor
-/web_src/fomantic/node_modules
-/web_src/fomantic/build/*
-!/web_src/fomantic/build/semantic.js
-!/web_src/fomantic/build/semantic.css
-!/web_src/fomantic/build/themes
-/web_src/fomantic/build/themes/*
-!/web_src/fomantic/build/themes/default
-/web_src/fomantic/build/themes/default/assets/*
-!/web_src/fomantic/build/themes/default/assets/fonts
-/web_src/fomantic/build/themes/default/assets/fonts/*
-!/web_src/fomantic/build/themes/default/assets/fonts/icons.woff2
-!/web_src/fomantic/build/themes/default/assets/fonts/outline-icons.woff2
+/web_src/fomantic
 /VERSION
 /.air
 /.go-licenses