Parse url path to extract query parameters from filename when calling embed.FS

[sapk]

I found that oauth-redirect.html is broken in latest version since it return 404 not found when query parameters are present (which are to be expected during an oauth process)

I think it was introduced in #100

This simply fix the issue by parsing the relative path with url.Parse before sending it to embed.FS.

I added a test similar to what is to be expected from an oauth process.
The same test previously passed successfully on v2.0.0.

[sapk]

Hi @ubogdan, sorry to ping you directly.
Could you please have a look at this PR ?

This bug block most oauth logic in swaggerui.

If you don't have time please ignore this message.
I can use my fork in the meantime but it could be great to upstream this fix.