Direct SVG rendering (#12157)

Introduce 'make svg' which calls a node script that compiles svg files
to `public/img/svg`. These files are vendored to not create a dependency
on Node for the backend build.

On the frontend side, configure webpack using `raw-loader` so SVGs can
be imported as string.

Also moved our existing SVGs to web_src/svg for consistency.

Fixes: https://github.com/go-gitea/gitea/issues/11618

package.json

@@ -30,9 +30,7 @@
     "monaco-editor-webpack-plugin": "1.9.0",
     "postcss-loader": "3.0.0",
     "postcss-preset-env": "6.7.0",
-    "svg-sprite-loader": "5.0.0",
-    "svgo": "1.3.2",
-    "svgo-loader": "2.2.1",
+    "raw-loader": "4.0.1",
     "swagger-ui": "3.28.0",
     "terser-webpack-plugin": "3.0.6",
     "tributejs": "5.1.3",
@@ -56,6 +54,7 @@
     "eslint-plugin-unicorn": "20.1.0",
     "stylelint": "13.6.1",
     "stylelint-config-standard": "20.0.0",
+    "svgo": "1.3.2",
     "updates": "10.2.15"
   },
   "browserslist": [