GitLab

- add package-lock.json to webpack/fomantic prereqs making them always rebuild when dependencies change.
- remove FOMANTIC_EVIDENCE. It seemed better to just track a few output files instead.
- delete fomantic output files before build to prevent possible bugs in fomantic's build.
- resolve WEBPACK_SOURCES only once for performance
- reorder variables for clarity
- use clean-all in Dockerfile
- detect busybox for find syntax

Fixes: https://github.com/go-gitea/gitea/issues/10569
Fixes: https://github.com/go-gitea/gitea/issues/10565
Fixes: https://github.com/go-gitea/gitea/issues/10570
Fixes: https://github.com/go-gitea/gitea/issues/10568