Add test dependencies via target-platform-configuration.

This is the forward compatible way and the previous one used via
tycho-surefire-plugin configuration is no longer supported from Tycho
0.21 onwards.
This is prerequisite for updating the build to use Tycho 0.21.

Change-Id: I1f82a3833b3f08239dc2136f23fea95e83798284
Signed-off-by: Alexander Kurtakov <akurtako@redhat.com>