Introduce a ComponentManagerRule to replace AbstractComponentTestCase

@ComponentList({
    DefaultExtensionLicenseManager.class
})
public class DefaultExtensionLicenseManagerTest
{
    @Rule
    public final ComponentManagerRule componentManager = new ComponentManagerRule();
...
    @Before
    public void setUp() throws Exception
    {
        this.licenseManager = this.componentManager.getInstance(ExtensionLicenseManager.class);
    }
...

@ComponentList({
    DefaultExtensionManagerConfiguration.class,
    DefaultLoggerManager.class,
    DefaultObservationManager.class
})
public class DefaultExtensionManagerConfigurationTest
{
    @Rule
    public final MockitoComponentManagerRule componentManager = new MockitoComponentManagerRule();

    private ExtensionManagerConfiguration configuration;

    private MemoryConfigurationSource source;

    @BeforeComponent
    public void registerComponents() throws Exception
    {
        // Register a Mocked Environment since we need to provide one.
        this.componentManager.registerMockComponent(Environment.class);

        // Register some in-memory Configuration Source for the test
        this.source = this.componentManager.registerMemoryConfigurationSource();
    }

    @Before
    public void setUp() throws Exception
    {
        this.configuration = this.componentManager.getInstance(ExtensionManagerConfiguration.class);
    }
...