Docs: Type annotation reference issues

current sphinx build has these warnings:

WARNING: Cannot resolve forward reference in type annotations of "openeo.rest.datacube.DataCube.execute_local_udf": name 'xarray' is not defined
WARNING: Cannot resolve forward reference in type annotations of "openeo.rest.vectorcube.VectorCube": name 'Connection' is not defined
WARNING: Cannot resolve forward reference in type annotations of "openeo.rest.mlmodel.MlModel": name 'Connection' is not defined
WARNING: Cannot resolve forward reference in type annotations of "openeo.rest.mlmodel.MlModel.load_ml_model": name 'Connection' is not defined
WARNING: Cannot resolve forward reference in type annotations of "openeo.rest.job.BatchJob": name 'Connection' is not defined
WARNING: Cannot resolve forward reference in type annotations of "openeo.rest.job.RESTJob": name 'Connection' is not defined
WARNING: Cannot resolve forward reference in type annotations of "openeo.rest.conversions.datacube_from_file": name 'XarrayDataCube' is not defined
WARNING: Cannot resolve forward reference in type annotations of "openeo.rest.conversions.datacube_plot": name 'XarrayDataCube' is not defined
WARNING: Cannot resolve forward reference in type annotations of "openeo.rest.conversions.datacube_to_file": name 'XarrayDataCube' is not defined
WARNING: Cannot resolve forward reference in type annotations of "openeo.rest.udp.RESTUserDefinedProcess": name 'Connection' is not defined
WARNING: Cannot resolve forward reference in type annotations of "openeo.udf.xarraydatacube.XarrayDataCube.plot": name 'matplotlib' is not defined

Reproduce the current Sphinx build and inspect the modules and objects named in the warnings, including DataCube.execute_local_udf, VectorCube, MlModel, BatchJob, RESTJob, the conversion functions, RESTUserDefinedProcess, XarrayDataCube.plot, and their referenced annotations. The work is done when the build completes without these unresolved type-annotation warnings.