Rewrite X509TrustManagerExtensionsTest

X509TrustManagerExtensionsTest used internal implementation details to
test X509TrustManagerExtensions#isUserAddedCertificate, these
implementation details are no longer the same and so this test failed to
catch the API being broken and then incorrectly flagged the fixed API as
broken.

To ensure that isUserAddedCertificate is properly covered the tests for
the API are split into two places: X509TrustManagerExtensionsTest covers
tests for the default case where there are no added CAs and
CaCertManagementTest to test the behavior when CAs have been added.

Bug:28262103
Change-Id: I14f3211c277fdc9c8bfc3d4ac932be375961fa28
2 files changed