tests: Implement IdentityManagementV2Fixture for v2::KeyChain

The old IdentityManagementFixture is renamed to IdentityManagementV1Fixture.

This commit also removes global KeyChainFixture, as it doesn't work with
TestKeyChain test suites.  Instead, IdentityManagementFixtures are
customizing PIB/TPM modules.

Change-Id: Iadc43b78523cd43bff4f454d6aea2fca8107a650
Refs: #2926
diff --git a/tests/wscript b/tests/wscript
index ad31f19..89a06cc 100644
--- a/tests/wscript
+++ b/tests/wscript
@@ -16,7 +16,7 @@
     # core modules that can be shared between unit and integrated tests
     bld(features="cxx",
         target="boost-tests-base",
-        source="key-chain-fixture.cpp identity-management-fixture.cpp",
+        source="identity-management-fixture.cpp",
         use='ndn-cxx tests-base BOOST',
         includes='.',
         install_path=None)