ENH: Factor out the 6-face neighbor code that is systemic through out the code base.

[imikejackson]

This utility file has common functions for dealing with the 6-face neighbor algorithm that is used throughout simplnx.

Plugins that are updated

SimplnxCore Plugin

Compatible	Completed	Tested	File	Notes
[ ]	[ ]	[ ]	RequireMinimumSizeFeatures.cpp	Another PR fixes this
[x]	[x]	[ ]	RequireMinNumNeighbors.cpp
[x]	[x]	[ ]	RemoveFlaggedFeatures.cpp
[x]	[x]	[ ]	ErodeDilateCoordinationNumber.cpp
[x]	[x]	[ ]	ErodeDilateBadData.cpp
[x]	[x]	[ ]	ErodeDilateMask.cpp	Only 1 of the 2 face-neighbor loops
[x]	[x]	[ ]	FillBadData.cpp
[x]	[x]	[ ]	ComputeBoundaryCells.cpp	Line 84 start
[x]	[x]	[ ]	ComputeEuclideanDistMap.cpp	Line 343 start
[ ]	[ ]	[ ]	ReplaceElementAttributesWithNeighborValues.cpp	Does not fall into this code schema. Skip File
[ ]	[ ]	[ ]	ComputeFeatureNeighborsFilter.cpp	Does not fall into this code schema. Skip

OrientationAnalysis Plugin

Compatible	Completed	Tested	File	Notes
[x]	[x]	[ ]	BadDataNeighborOrientationCheck.cpp	Start on line 99
[x]	[x]	[ ]	NeighborOrientationCorrelation.cpp	Start line 233

[nyoungbq]

Looks great! Found one place in the supplied files that was missed. This definitely improves the readability of the whole thing.