This allows us to correctly handle "indexed" vector tile sets,
where higher zoom level tiles may be missing where a lower
zoom level tile is deemed to have sufficient detail for higher
zoom levels.
This gives more flexibility in future to handle known missing tiles or
other special circumstances (eg falling back to lower
zoom level tiles from the matrix set in certain circumstances)
E.g. when a vector tile connection has a manually set zoom level
range which doesn't include level 0, we still need this available
for correct tile feature decoding
Fixes#47934
correct place
This fixes the rendering of vector tiles layers which are constructed
in any non web mercator CRS.
(Unfortunately the required information is not recorded in mbtiles
packages, so it's necessary to set the correct parameters via
API calls when trying to load non-3857 mbtiles.)
XYZ convention has zero Y at the top and increasing downwards,
but various map servers use TMS convention which has zero Y at
the bottom and rising upwards (within tile matrix)
