Implement rootpath similar to argo-cd

# Summary

Currently, running argo-workflows on a subpath requires rewrites on the reverse proxy. In argo-cd you can avoid that by setting extra arguments to the entrypoint command.
```
- --rootpath
- /argocd
- --basehref
- /argocd
```
Would it be possible to replicate this behavior on argo-workflows as well?

# Use Cases

AWS Application Load Balancers do not support rewrites. Our setup doesn't use any additional controller like nginx.

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**Message from the maintainers**:

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Start by tracing the argo-workflows entrypoint command and the handling of request paths, links, and assets, then compare the requested --rootpath and --basehref behavior with argo-cd. Identify the relevant tests before making changes. Done means the service works from a configured subpath without reverse-proxy rewrites, including navigation and static assets.

Written by the indexing model from the issue text.