fix when baseUrl and routeUrl is not the same

[Diluka]

Fix problems that cannot be accessed when and are not the same

scenario	listenOpts.basePath	app.locals.appBasePath
standalone	use to mount route	keep empty
middleware	external base path	the same

usage example

const url = new URL(config.get('server.url'));
app.use(
  '/arena',
  basicAuth({ users: { user: 'pass' }, challenge: true }),
  Arena(
    {
      queues: [
        {
          name: 'default',
          hostId: '默认',
          redis: config.get('redis[2]'),
        },
      ],
    },
    {
      disableListen: true,
      basePath: url.pathname,
    },
  ),
);

fix #162

[softbrix]

I like this configuration. Works as I expected. Downloaded this branch as a temporary fix until this is merged and deployed to npm.

[softbrix]

Small update after som more testing.
I had to configure the basePath like this for it to work when the application was hosted on the root path:
basePath: baseUrlPath != '/' ? baseUrlPath : undefined,

Dunno but I think this should be handled by the configuration so I don't need to set the basepath to 'undefined' since '/' is the default behaviour.

[skeggse]

#123 (review):

This has been a long-requested feature. I'd like to move this along, but still don't have a ton of time to review. I don't immediately understand the distinction between the appBasePath and the mountPath. Along those lines, could we get some documentation in the readme describing how the new option functions and how it differs from the old?

[JoJ123]

@Diluka @softbrix @skeggse We are facing the same issue, can't use arena anymore with AppGateway. Is there a change that this will be released soon? This UI has some benefits vs other Bull UIs in the market.