Support creating a new workspace client from an account client

[mgyucht]

Changes

This PR introduces func (a *AccountClient) GetWorkspaceClient(w provisioning.Workspace) (*WorkspaceClient, error) to make it easy to get a workspace client for a given workspace. The workspace client uses a copy of the config from the account client, reusing the underlying authenticator as well. This allows all workspace clients to use the same underlying token when authenticating with OAuth, decreasing the number of unnecessary token refreshes. Additionally, it allows workspace clients to work with U2M OAuth using the account-level token for customers with Unified Login.

Use-case: databricks/terraform-provider-databricks#3188

Tests

New example passes.

• make test passing
• make fmt applied
• relevant integration tests applied

[pietern]

Can you comment when we have a DeploymentName and when we have to use the AzureResourceID?

[mgyucht]

Because the deployment name is always present when fetching a workspace, we don't actually have any hard dependency on the AzureResourceID field being set for the core functionality of the Config. In fact, because we are copying the auth field, we don't have to preserve any of the fields that are used for configuration. I've simply implemented this because we can compute the AzureResourceId from the Workspace.

[pietern]

If we expect this to only work with OAuth, should this be enforced?

I.e. if folks try to use this with username/password it will certainly not work.

[mgyucht]

Why wouldn't it work with username and password? E2 accounts where a user logs in with username/password will use the same username/password at the workspace and account-level. (Our integration tests use basic auth, and this works there.) I think the only scenario where this wouldn't work is if a customer configured workspace-level SSO.

[codecov-commenter]

Codecov Report

Attention: 3 lines in your changes are missing coverage. Please review.

Comparison is base (1d9a465) 18.45% compared to head (7bd1f47) 18.59%.
Report is 1 commits behind head on main.

Files	Patch %	Lines
config/config.go	90.32%	2 Missing and 1 partial ⚠️

Additional details and impacted files

@@            Coverage Diff             @@
##             main     #792      +/-   ##
==========================================
+ Coverage   18.45%   18.59%   +0.13%     
==========================================
  Files         115      116       +1     
  Lines       21321    21357      +36     
==========================================
+ Hits         3935     3971      +36     
  Misses      17144    17144              
  Partials      242      242              

☔ View full report in Codecov by Sentry.
📢 Have feedback on the report? Share it here.