[JENKINS-19146] Triggers works with Flexible Publish plugin

Flexible Publish plugin excludes Build Trigger and [Parameterized Build Trigger](https://wiki.jenkins-ci.org/display/JENKINS/Parameterized+Trigger+Plugin).
This is for these Trigger publishers triggers downstream builds not with `Publisher#perform`, but using `DependencyGraph`. See [JENKINS-12418](https://issues.jenkins-ci.org/browse/JENKINS-12418) for details.

My idea is evaluating conditions in dependency calcurations by creating wrapped `DependencyGraph` and `Dependency` classes (`ConditionalDependencyGraphWrapper` and `ConditionalDependencyWrapper`).
This enables us to trigger downstream builds conditionally.