fix(server): wash app delete command returns success for invalid application name

[ffuerste]

Feature or Problem

If an incorrect model name is passed without a version to the wash app del <app_name> command, it still outputs a success message ("Deleted application: <app_name>") even though this app does not exist.

Related Issues

closes #502

Release Information

This PR fixes a non-critical issue. It can therefore be safely included in the next version.

Consumer Impact

This PR adapts the lookup logic for deletion requests, so that also for non-existing models a DeleteResult::Noop result is returned if no version is specified. This changes the current return value (which is DeleteResult::Deleted).

Currently, the documented and recommended way to delete applications is to use the wadm-client crate. The wadm-client create interprets both delete results as a success:

        match body.result {
            DeleteResult::Error => Err(ClientError::ApiError(body.message)),
            DeleteResult::Noop => Ok(false),
            DeleteResult::Deleted => Ok(true),
        }

The wash CLI uses the wadm-client crate internally and outputs based on the contained result value (true or false) different output messages.

Testing

Unit Test(s)

No unit tests have been added or updated.

Acceptance or Integration

An additional test case was added to the test_delete_noop integration test (covering the deletion of a non-existing model without specifying a version).

[thomastaylor312]

Excellent work here @ffuerste. Thanks for the fix and additional test!