Sync with PALEOboxes v0.22 / PALEOmodel v0.16 dimensions / coordinates updates

[sjdaines]

See PRs:
PALEOtoolkit/PALEOboxes.jl#151
PALEOtoolkit/PALEOmodel.jl#107

Example of change needed from ReactionSedimentGridn1D do_sediment_setup_grid:

# attach coordinates to grid for output visualisation etc
if isdefined(PB, :set_coordinates!) # PALEOboxes >= 0.22
    PB.set_coordinates!(rj.domain.grid, "cells", ["zmid", "zlower", "zupper"])
else
    empty!(rj.domain.grid.z_coords)
    push!(rj.domain.grid.z_coords, PB.FixedCoord("zmid", grid_vars.zmid, PB.get_variable(m, "zmid").attributes))
    push!(rj.domain.grid.z_coords, PB.FixedCoord("zlower", grid_vars.zlower, PB.get_variable(m, "zlower").attributes))
    push!(rj.domain.grid.z_coords, PB.FixedCoord("zupper", grid_vars.zupper, PB.get_variable(m, "zupper").attributes))
end