* move semantic.dropdown.custom.js to webpack
Also disabled a annoying linter rule which insisted that imports can not
contain a file extension.
Fixes: https://github.com/go-gitea/gitea/issues/8971
* reorganize web_src files and rebuild
* restart ci
- moved gitgraph.js to web_src and made it importable and es6-compatible
- created new webpack chunk for gitgraph
- enabled CSS loader in webpack
- enabled async/await syntax via regenerator-runtime
- added script to ensure webpack chunks are loaded correctly
- disable terser's comment extraction to prevent .LICENCE files
gitgraph.js has many issues:
1. it is incompatible with ES6 because of strict-mode violations
1. it does not export anything
1. it's css has weird styles like for `body`
1. it is not available on npm
I fixed points 1-3 in our version so it's now loadable in webpack. We should eventually consider alternatives.
