Matlab object loading functions (see #10383)

This PR adds a couple of utility functions to OMERO.matlab to load objects (`getProjects`, `getDatasets`,...)

No integration tests have been added so far as no adequate infrastructure exists in Matlab. Should we wait until we have 1- a concrete plan to reuse OmeroJava test libraries and 2- new `deleteExperimeter()` and `deleteGroup()` functions?
/cc @bpindelski