Angus/hips remote image load

[veggiesaurus]

Description
Load files from the hips2fits server

• What is implemented or fixed? Mention the linked issue(s), if any.
  Closes Support for loading HiPS FITS images #1379

• How does this PR solve the issue? Give a brief summary.
  Use CartaFitsLoader to open the file using the URL as the filename.

• Are there any companion PRs (frontend, protobuf)?
  Angus/remote file requests carta-frontend#2346, initial work on remote file requests carta-protobuf#93

• Is there anything else that testers should know (e.g. exactly how to reproduce the issue)?
  Load HiPS FITS image using the frontend data query UI.

Checklist

• changelog updated / no changelog update needed
• e2e test passing / corresponding fix added / new e2e test created
• ICD test passing / corresponding fix added / new ICD test created
• protobuf updated to the latest dev commit / no protobuf update needed
• protobuf version bumped / protobuf version not bumped
• added reviewers and assignee
• added ZenHub estimate, milestone, and release

[veggiesaurus]

@pford Do you think this is on the right track? this is for loading HIPS files from the hips2fits service using cfitsio's ability to load from URL. Some of the changes are required to avoid opening files multiple times

@confluence can we assign this to you or @confluence for cleanup/testing once the frontend is fleshed out? (it's only scripting at the moment)

[github-actions]

Package	Line Rate	Health
src.Cache	72%	➖
src.DataStream	44%	➖
src.FileList	67%	➖
src.Frame	36%	❌
src.HttpServer	42%	➖
src.ImageData	28%	❌
src.ImageFitter	83%	✔
src.ImageGenerators	43%	➖
src.ImageStats	75%	✔
src.Logger	37%	❌
src.Main	52%	➖
src.Region	69%	➖
src.Session	4%	❌
src.Table	52%	➖
src.ThreadingManager	67%	➖
src.Timer	85%	✔
src.Util	38%	❌
Summary	46% (8620 / 18893)	➖