Additional default interpolators for unstructured grids

[fluidnumerics-joe]

In PR #2319 , We didn't want to provide automatic interpolator assignment, due to the fact that some interpolators are not currently provided (e.g. on an edge), but we didn't want to prevent someone who is building a new interpolator from leveraging this new from_fesom2 method.

Some datasets, like the ones we've been working with, have variables that are on multiple locations (e.g. faces and nodes), so having a single argument for interpolation wouldn't cover all cases for a dataset.

With other requests coming in to support other models, it's clear we need more interpolators

• Add ICON unstructured/generic dataset #2075 - ICON has edge registered variables. Resolving this issue requires also handling vector rotation as well which is not planned to be addressed here.
• Provide built-in 3D interpolation method node-registered but vertically centered data for unstructured grids #2250 - indicates that some fesom velocity fields can be defined on vertices but may be vertically centered.

In this issue, the focus is to provide basic interpolators (with tests and documentation) for the cross product of

(face, edge, node) X (vertical, vertical face)