[ENH] - Force the trailing slash when using jupyter server proxy

[Adam-D-Lewis]

Feature description

More info: #2273, nebari-dev/nebari-docs#240 (comment)

I see that if a process (panel, r-shiny, etc.) returns a relative path e.g. jquery-3.6.0/jquery.min.js then you must use a trailing slash when accessing the process through jupyter-server-proxy. e.g. https://nebari.quansight.dev/user/[email protected]/proxy/5333/ instead of https://nebari.quansight.dev/user/[email protected]/proxy/5333. The trailing slash is important.

Otherwise, you get the issue described in #2273.

Anything else?

No response

[Adam-D-Lewis]

I tested which visualization libraries require the closing slash at least for simple apps and found that even simple panel and r-shiny apps will break without the path, but really any could use a relative path and users would experience the same issue.