chore: Clean up error handling around Hub client requests

[jstlaurent]

Changelogs

• Simplify error handling around requests to the Polaris Hub
• Wrap lower-level errors in PolarisHubError, to have more helpful messages

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Checklist:

• Was this PR discussed in an issue? It is recommended to first discuss a new feature into a GitHub issue before opening a PR.
• Add tests to cover the fixed bug(s) or the newly introduced feature(s) (if appropriate).
• {Update the API documentation if a new function is added, or an existing one is deleted.~
• Write concise and explanatory changelogs above.
• If possible, assign one of the following labels to the PR: feature, fix, chore, documentation or test (or ask a maintainer to do it for you).

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I noticed that we had some type incompatibilities when instanciating PolarisHubError, around the response object passed in. I corrected this, and took the opportunity to simplify and straighten
up the error handling around the client's requests to the Hub. It should now do a better job at surfacing PolarisHubError, which have nicer user facing messages than the underlying errors.

[mercuryseries]

Thanks, @jstlaurent 💅!

[cwognum]

Thank you, @jstlaurent !