Resolve compatibility conflicts with PyAirbyte (rename library and rebuild)

[aaronsteers]

Currently, this package (airbyte-api) imports with import airbyte. The new PyAirbyte library also imports with import airbyte.

I'm starting to work through this issue, trialing a few approaches in

• Change (breaking!): Rename import to airbyte_api to make airbyte-api compatible with PyAirbyte #66

Options I'm aware of:

1. Rename the package to something like airbyte_api or airbyte_cdk.
2. Create a namespaces package, where airbyte-api imports as airbyte.sdk, which would be grafted into the same top-level airbyte namespace as PyAirbyte, but withought the two packages conflicting.

[aaronsteers]

Reopening because we ran into issues with the build process, specifically in accessing the post-gradle version of the OpenAPI spec as input.