feat: Subject Segmentation - added SubjectSegmenterOptions

[bensonarafat]

@fbernaly
In the native code, I separated each separately with a method. e.g. addForegroundBitmap and addConfidenceMask
Segmenter options are as follows:

1. Foreground confidence mask
2. Foreground bitmap
3. Multi-subject confidence mask
4. Multi-subject bitmap

I used the Multi-subject confidence mask in the example app, but any of the options can be enabled.