Update daskhub's to use dask-gateway version 2022.4.0

[consideRatio]

I've cut a release and updated JMTE to use version 2022.4.0 of dask-gateway.

See the changelog on how to upgrade the Helm chart. It should not be a breaking change if users have the 0.9.0 dask-gateway client installed in their images still.

[consideRatio]

I labelled this as support as its now also something wishes for us to have in the LEAP hub.

I suggest that we get #1251 merged to close #1258, and then whoever in @2i2c-org/tech-team is willing, goes for it by first opening a PR to update the dask-gateway version, and then before merge applies the new CRDs according to the changelog notes to each cluster (once per cluster, not once per hub) we have that maintain that use dask-gateway.

[GeorgianaElena]

I've just assigned myself to this since I'm currently investigating the schema validation errors that came up in https://github.com/GeorgianaElena/pilot-hubs/tree/bump-dask-gateway.

Also, I think it's quite important and shouldn't take long, so I'm giving this a try now.

[consideRatio]

Looking at dask-gateway's helm chart's default values.yaml file, i see extraConfig listed under gateway.extraConfig while I saw an error listed about us declaring dask-gateway.extraConfig instead of dask-gateway.gateway.extraConfig. The schema catches actual misconfiguration errors wieee!