Ct 276/iceberg support patch

[VersusFacit]

resolves #432

Description

Patches to dparent1's pr here.

I have addressed all comments that I could find open/unaddressed in their PR. I also rewrite the bulk of the list_relations_without_caching method.

Me running some runs against my dockerized iceberg instance.

Checklist

• [x] I have read the contributing guide and understand what's expected of me
• [x] I have signed the CLA
• [x] I have run this code in development and it appears to resolve the stated issue
• [x] This PR includes tests, or tests are not required/relevant for this PR
• [x] I have opened an issue to add/update docs, or docs changes are not required/relevant for this PR
• [x] I have run changie new to create a changelog entry

[dparent1]

I've run my original testcase with this change and it is working for me! Thanks so much for this @VersusFacit, I'll close my other PR.

[Fokko]

Thanks @dparent1 for creating the PR and @VersusFacit & @mikealfare for picking this up! Great to see this happening!

[dparent1]

Thanks @dparent1 for creating the PR and @VersusFacit & @mikealfare for picking this up! Great to see this happening!

This made my day when I turned my computer on this morning. Also @Fokko was very much instrumental in keeping this PR alive, thanks goes to you as well as the others.