Phase correlation should be an initializer

[dicengine]

In DICe::Schema, there is a lot of code that could be encapsulated in a DICe::Initializer related to when phase correlation of the whole image is used for the initial guess. Remove the member data like phase_cor_u_x_, etc. and put this in a new initializer class.

[dicengine]

Phase correlation is now an initializer, same as field values and neighbor values initializers too