[dagster-sdf] Add Project Scaffold

[akbog]

Summary & Motivation

This PR contains the dagster-sdf scaffolding cli, which helps users quickly scaffold a dagster project from an existing sdf workspace.

dagster-sdf workspace scaffold --project-name {dagster-project-name} --sdf-workspace-dir {path-to-sdf-workspace}

It creates the necessary assets.py, constants.py, definitions.py etc. to get a project off the ground.

Users can then run dagster dev, with DAGSTER_SDF_COMPILE_ON_LOAD=1 to ensure the project is compiled before the information schema is loaded to determine the asset dag.

DAGSTER_SDF_COMPILE_ON_LOAD=1 dagster dev

How I Tested These Changes

See dagster_sdf_tests/cli.

[cmpadden]

@akbog when attempting to use the scaffold command with a test sdf project:

$ dagster-sdf workspace scaffold --project-name example_sdf_project --sdf-workspace-dir dagster_sdf_tests/sdf_workspaces/moms_flower_shop
$ cd example_sdf_project/
$ DAGSTER_SDF_COMPILE_ON_LOAD=1 dagster dev

I received this error:

The above exception was caused by the following exception:
pydantic.error_wrappers.ValidationError: 1 validation error for SdfCliResource
workspace_dir
  /Users/colton/src/dagster/python_modules/libraries/dagster-sdf does not contain an workspace.sdf.yml file. Please specify a valid path to an sdf workspace. (type=value_error)

Despite the workspace file being present in the target project:

$ file dagster_sdf_tests/sdf_workspaces/moms_flower_shop/workspace.sdf.yml
dagster_sdf_tests/sdf_workspaces/moms_flower_shop/workspace.sdf.yml: ASCII text

Am I intended to copy the sdf project or workspace file to a new location?

[cmpadden]

Confirmed working as expected locally, and tests are running green in bk.

I'd like to land this tonight so that you and Nick can leverage this in dogfooding tomorrow! We can continue to iterate if/when things come up. Cheers.