CDI: improve PackagingFilter performance by avoiding costly opeation in loop

[NicolaIsotta]

Discovered this bottleneck while working on other things.
The current version recreates the ClasspathInfo every iteration of the loop, causing a remarkable slowdown; this PR introduces a lazily-inizialized resusable ClasspathInfo.
In one of my test cases (@Inject on a java.util.Map), the boost was ≃ 10x (time spent in the method went down from 2 secs to less than 200 millis).

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