Add resource for UC schemas to DABs

[shreyas-goenka]

Changes

This PR adds support for UC Schemas to DABs. This allows users to define schemas for tables and other assets their pipelines/workflows create as part of the DAB, thus managing the life-cycle in the DAB.

The first version has a couple of intentional limitations:

1. The owner of the schema will be the deployment user. Changing the owner of the schema is not allowed (yet). Tangentially related, but run_as will also not affect UC resources like a schema or registered model. Lets limit the scope of run_as to the compute identity used instead of ownership.
2. API fields that are present in the update API but not the create API. For example: enabling predictive optimization is not supported in the create schema API and thus is not available in DABs at the moment.
3. Force destroy for schemas. Schema deletion/bundle destroy will fail if the schema has data in it. Support for force destroy for schemas can be added as a followup, as a command line flag. The HTTP API does not support force deletes (the SQL API does via the CASCADE key), so we would have to use the volumes / tables / models / functions APIs to manually delete all of them before deleting the schema. This is how terraform does it today.

Note: This PR requires #1414 to be merged.

Tests

Manually and integration test. Manually verified the following work:

1. Development mode adds a "dev_" prefix.
2. Modified status is correctly computed in the bundle summary command.
3. Grants work as expected, for assigning privileges.
4. Variable interpolation works for the schema ID.