Reorganize frontend files and tooling (#10168)

- move "vendor" files to js/vendor and less/vendor
- move swagger to js/standalone (meant for standalone pages)
- move gitgraph to features and streamline its loading
- add linting configs to webpack dependencies in make
- set ignored files for eslint/stylelint directly in their configs

Co-authored-by: Lunny Xiao <xiaolunwen@gmail.com>
Co-authored-by: zeripath <art27@cantab.net>
Co-authored-by: Antoine GIRARD <sapk@users.noreply.github.com>

webpack.config.js

@@ -24,7 +24,7 @@ module.exports = {
       resolve(__dirname, 'web_src/less/index.less'),
     ],
     swagger: [
-      resolve(__dirname, 'web_src/js/swagger.js'),
+      resolve(__dirname, 'web_src/js/standalone/swagger.js'),
     ],
     jquery: [
       resolve(__dirname, 'web_src/js/jquery.js'),