fix: cli fails when listing providers [DET-10127]

[eecsliu]

Description

In EE, the CLI returns an error when listing auth providers but auth is not being used. This is because we are always expecting a list, but we receive null in this case, hence the error 'NoneType' has no len(). This fix updates the CLI to catch null values and not fail the length check.

Test Plan

Run a devcluster on EE with the oidc config field populated with something like:

      oidc:
          authentication_claim: email
          auto_provision_users: false
          client_id: ''
          client_secret: ''
          enabled: false
          idp_recipient_url: ''
          idp_sso_url: ''
          provider: ''
          scim_authentication_attribute: userName

Run the cli command det auth list-providers - the CLI should return No SSO providers found.

Commentary (optional)

Checklist

• Changes have been manually QA'd
• User-facing API changes need the "User-facing API Change" label.
• Release notes should be added as a separate file under docs/release-notes/.
  See Release Note for details.
• Licenses should be included for new code which was copied and/or modified from any external code.

Ticket

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[wes-turner]

if not sso_providers:

should be sufficient. bool(<empty_list>) evaluates to False.

[eecsliu]

fixed! thanks

[codecov]

Codecov Report

Attention: Patch coverage is 0% with 1 lines in your changes are missing coverage. Please review.

Project coverage is 47.52%. Comparing base (a8ac657) to head (e309fd3).
Report is 17 commits behind head on main.

Additional details and impacted files

@@            Coverage Diff             @@
##             main    #8903      +/-   ##
==========================================
- Coverage   47.53%   47.52%   -0.01%     
==========================================
  Files        1066     1066              
  Lines      170248   170248              
  Branches     2235     2237       +2     
==========================================
- Hits        80919    80915       -4     
- Misses      89171    89175       +4     
  Partials      158      158              

Flag	Coverage Δ
backend	43.34% <ø> (-0.01%)	⬇️
harness	63.77% <0.00%> (-0.01%)	⬇️
web	42.50% <ø> (ø)

Flags with carried forward coverage won't be shown. Click here to find out more.

Files	Coverage Δ
harness/determined/cli/sso.py	19.78% <0.00%> (ø)

... and 4 files with indirect coverage changes

[wes-turner]

LGTM!