[magics] Add options to include the API url & key with alias

[srdas]

In PR #1471 we added the option to pass the API url and key name in the code cell when using %%ai magics. After the model or alias, we pass either or both --api-base and --api-key-name as needed.

Here, we add the ability to include the api-base and/or api-key-name in the alias, which streamlines the use of the alias in magics. Users no longer have to pass the API url and key-name in each magics call. The following examples illustrate the usage:

Use an alias with no API options:

Use the alias with base API url options:

Use the alias with base API url and key-name options:

Updated the tests in test_magics.py for the new arguments and also re-tested all other magics features.

[dlqqq]

This is awesome, thank you! Code changes look good.