Allow translation cts can add itself into allowlist for content capture

The UiTranslationManager APIs need the token that report by the
content capture, we need to have a test ContentCaptureService for
translation cts to test UiTranslationManager. So we also allow
translation cts can add itself into allow list.

Bug: 179047265
Test: atest CtsContentCaptureServiceTestCases
Test: atest CtsTranslationTestCases to make sure the service can be
connected
Change-Id: I15874ce6fc68dbb5fba0a51cf74899d2dec9bae1