Support Additional FESOM2 Grid Formats (#1013)

* update grid-formats.rst

* add boilerplate for fesom2 reader

* initial logic for face_nodes

* add fesom soufflet grid

* add pi mesh

* add fesom test file

* add reader for edge_tri and edges, add docstrings

* cleanup and write test

* add FESOM2 to docs

* remove dist files

* add tests

* update tests

* update logic and error handling in from_dataset

* update FESOM2 section in user guide

* add cell-centered data variable for testing

Author: philipc2

docs/user-guide/grid-formats.rst

@@ -140,12 +140,10 @@ References
 
 FESOM2
 ======
-The F**inite volumE Sea Ice-Ocean Model (FESOM2) is a Multi-resolution ocean general circulation
+The Finite Volume Sea Ice-Ocean Model (FESOM2) is a Multi-resolution ocean general circulation
 model that solves the equations of motion describing the ocean and sea ice using finite-volume methods
 on unstructured computational grids. The model is developed and supported by researchers at the
-Alfred Wegener Institute, Helmholtz Centre for Polar and Marine Research (AWI), in Bremerhaven, Germany. UXarray
-currently supports reading the ``fesom.mesh.diag.nc`` file that is generated and encoded in the UGRID conventions.
-
+Alfred Wegener Institute, Helmholtz Centre for Polar and Marine Research (AWI), in Bremerhaven, Germany.
 
 References
 ----------