Add configurable maximiumPoseAmbiguityThreshold for use in PhotonPoseEstimator

[JohnGilb]

When cameras are distant from AprilTags, it's quite common to have very high pose ambiguities, leading to significant deviations in estimated pose. Since the PhotonPoseEstimator calls camera.getLatestResult() internally, there's no opportunity for user code to check the values in that result and do any filtering of their own.

This PR adds a configurable threshold, via setMaximumPoseAmbiguityThreshold(double maximumPoseAmbiguityThreshold), that is used in the update() method of PhotonPoseEstimator to remove any targets with high pose ambiguities from consideration by the various strategies.

[mdurrani808]

Any updates?

[JohnGilb]

I have somebody on my team with C++ background, but not sure if they'll have the time to implement that before Week 1 competitions.