feat: 🎸 Add --regions and --exclude flag to fetch_azure

[sunny0826]

refer #2549
Add --regions and --exclude flag to fetch_azure.

--regions: Fetch the list of specified regions.
--exclude: Exclude the list of specified regions.

example:

# Fetch the specified regions for Azure
python -m sky.clouds.service_catalog.data_fetchers.fetch_azure --regions japaneast australiaeast uksouth
# Exclude the specified regions for Azure
python -m sky.clouds.service_catalog.data_fetchers.fetch_azure --exclude centralus eastus

[iojw]

Thank you for the PR @sunny0826! I've left some comments.

Could also also create a new issue to add the same flags for the GCP fetching script? It would be good to have parity across these 2 scripts.

[sunny0826]

@iojw An Issue #2555 about GCP has been created.

[iojw]

Thank you @sunny0826! Just some minor nits, this is almost good to go.

[iojw]

Thank you @sunny0826! I made some minor fixes but this is good to go. It will be very helpful for the future.