Make reagent dispensers gridinv-based instead of pseudo-listinv (#34205)

Make reagent dispensers gridinv-based instead of pseudo-listinv (#34205)

This simplifies the code and makes the experience of examining contents
easier without the reagent dispenser UI, as well as adding the possibility
for dispensers to have items of heterogeneous sizes in them, which would
allow configuring reagent dispensers to accept smaller containers such
as beakers or vials in order to allow for more types of smaller quantities
of reagents, or other flexibilities brought by using a standard storage
component.