Add utility methods for catalog and schema creation to the AI Functio… (

unitycatalog#765)

…n client for OSS

**PR Checklist**

- [X] A description of the changes is added to the description of this
PR.
- [ ] If there is a related issue, make sure it is linked to this PR.
- [ ] If you've fixed a bug or added code that should be tested, add
tests!
- [ ] If you've added or modified a feature, documentation in `docs` is
updated

**Description of changes**

Adds the `create_catalog` and `create_schema` utility methods to the
client to simplify the experience for users of the AI function client
(along with the base async API handlers for these sync methods). Updates
the quickstart to greatly simplify the process for running the tutorials
for getting started (the previous examples were a tad intimidating).

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Signed-off-by: Ben Wilson <[email protected]>