Forward model magnetic properties of prism_layer

[markgrujic]

Description of the desired feature:

There are certain scenarios where forward modelling the magnetic effect of layers is meaningful (e.g. topography). It seems that prism_layer can be used to define these layers and perhaps even assign magnetic properties, however there does not appear to be a mag equivalent to prism_gravity to perform the forward operation for the magnetic field. I can think of some things that would be needed, including:

• harmonica.prism_magnetic, jit_prism_magnetic, and new kernels for different mag fields that would need inducing field parameters
• magnetic() defined in DatasetAccessorPrismLayer so that prism_layer.magnetic could call harmonica.prism_magnetic
• new constants defined
• changes to the dispatcher to account for gravity or mag

Are you willing to help implement and maintain this feature?

Happy to help where I can, probably best suited to testing though!