Tasks: Ensure workspace delegate and scope defined

[colin-grant-work]

What it does

Fixes #10575 by ensuring that both the scope of workspace delegate and the delegate itself are defined in the TaskConfigurationManager.

Closes #10497

How to test

1. Open the application with no workspace.
2. In the frontend logs, see no message about inabililty to read property scope of undefined.

Review checklist

• As an author, I have thoroughly tested my changes and carefully followed the review guidelines

Reminder for reviewers

• As a reviewer, I agree to behave in accordance with the review guidelines

[vince-fugnitto]

The changes look good to me, I confirmed that on master the following error exists while this pull-request resolves the issue:

logger-protocol.ts:112 root ERROR TypeError: Cannot read properties of undefined (reading 'toString')
    at TaskConfigurations.getKeyFromScope (http://localhost:3000/packages_task_lib_browser_quick-open-task_js.bundle.js:1744:22)
    at TaskConfigurations.readTasks (http://localhost:3000/packages_task_lib_browser_quick-open-task_js.bundle.js:1570:26)
    at TaskConfigurations.refreshTasks (http://localhost:3000/packages_task_lib_browser_quick-open-task_js.bundle.js:1562:20)
    at TaskConfigurations.onDidTaskFileChange (http://localhost:3000/packages_task_lib_browser_quick-open-task_js.bundle.js:1554:28)
    at http://localhost:3000/packages_task_lib_browser_quick-open-task_js.bundle.js:1401:28
    at http://localhost:3000/bundle.js:141256:69
    at CallbackList.invoke (http://localhost:3000/bundle.js:141262:26)
    at Emitter.fire (http://localhost:3000/bundle.js:141374:29)
    at TaskConfigurationManager.updateWorkspaceModel (http://localhost:3000/packages_task_lib_browser_quick-open-task_js.bundle.js:1152:47)
    at TaskConfigurationManager.<anonymous> (http://localhost:3000/packages_task_lib_browser_quick-open-task_js.bundle.js:1013:18)