Rio-tiler

* Fix inverted col/row check when doing window read of a non WarpedVRT dataset

* add `rio_tiler.mosaic.mosaic_point_reader` function to create Point value from multiple observation
python
def reader(asset: str, *args, **kwargs) -> PointData:
with Reader(asset) as src:
return src.point(*args, **kwargs)

pt: PointData = mosaic_point_reader(["cog.tif", "cog2.tif"], reader, 0, 0)

* fix invalid definition of `PointData.mask` when mask is not provided. Makes sure it's a one element array.

* raise `InvalidPointDataError` error when trying to create PointData from an empty list in `PointData.create_from_list`

* fix invalid coordinates slicing for `XArrayReader.point()` method (author benjaminleighton, https://github.com/cogeotiff/rio-tiler/pull/559)

* add `asset_as_band` option in `MultiBaseReader` tile, part, preview, feature and point methods

python
with STACReader(STAC_PATH) as stac:
img = stac.tile(71, 102, 8, assets="green")
assert img.band_names == ["green_b1"]

with STACReader(STAC_PATH) as stac:
img = stac.tile(71, 102, 8, assets="green", asset_as_band=True)
assert img.band_names == ["green"]

For expression, without `asset_as_band` tag, users have to pass `_b{n}` suffix to indicate the band index
with STACReader(STAC_PATH) as stac:
img = stac.tile(71, 102, 8, expression="green_b1/red_b1")
assert img.band_names == ["green_b1/red_b1"]

with STACReader(STAC_PATH) as stac:
img = stac.tile(71, 102, 8, expression="green/red", asset_as_band=True)
assert img.band_names == ["green/red"]