Let LBP2D work on IterableInterval

Currently `LBP2D` only works on `RandomAccessibleInterval`s. However, there should be a way (e.g. via conversion) to also compute this feature on `IterableInterval`s, especially `LabelRegion`s. We just have to think about how to handle values inside the `Interval` but outside the `LabelRegion`. One idea is to pass a `RandomAccess` on the source image + the `LabelRegion`, such that the original values of the image are used outside the `LabelRegion`.

see: https://github.com/imagej/imagej-ops/blob/master/src/main/java/net/imagej/ops/features/lbp2d/DefaultLBP2D.java

Start by reading src/main/java/net/imagej/ops/features/lbp2d/DefaultLBP2D.java and tracing how LBP2D currently accepts RandomAccessibleIntervals. Investigate how IterableIntervals, especially LabelRegions, expose values outside the region; done means defining and implementing a supported conversion or access pattern with behavior for those values.

Written by the indexing model from the issue text.