text-overlap and icon-overlap

[wipfli]

maplibre/maplibre-gl-js#347 added text-overlap and icon-overlap which deprecated the booleans text-allow-overlap and icon-allow-overlap. The new properties take three possible values

never: same as -allow-overlap false
always: same as -allow-overlap true
cooperative: the overlap mode of the previously-placed symbol is checked. The placement is accepted if the previously-placed symbol is also using -overlap: 'cooperative' or -overlap: 'always'. If the previously-placed symbol is using -overlap: 'never', the new symbol's placement is rejected.

Thanks @drwestco (Azure Maps) for the implementation in GL JS!