chore: introduce tests for ManageService component

[benbrown]

Description

Adds a suite of unit test cases for the base ManageService component (which is in turn used to create the ManageLuis, ManageQNA and ManageSpeech components)

Tests so far:

• Test that the component renders with the correctly customized ui text
• Test that the "select an existing resource" path works as expected
• Test that the "Create a new resource" path works as expected
• Test that the "Create a new resource" path works when a tier selection is provided
• Test that the cancel button calls the right callback
• Tests that the data is sent back to the calling component when user has completed session
• Test that the "createService" prop is called (this is where the other components inject their specific details)

This involved creating simple mocks for a variety of Azure ARM APIs.

Still to come:

• test ManageLuis directly
• test ManageSpeech directly
• test ManageQNA directly (hardest)

Task Item

Fixes #7902

[coveralls]

Coverage increased (+0.7%) to 51.189% when pulling d97e541 on benbrown/manageservicetests into 5d443a4 on main.

[pavolum]

Component tests are generally in client/__tests__/components and in this PR they are siblings of the tested components dir