Xsar

fix for attributes of the `datatree`

fix FRAME of orbit missing, and change type of definition attr in geolocation_annotation dataset

fix missing variable `lineSpacing` and `sampleSpacing`

fix issue with method `Sentinel1Dataset.get_ll_from_SLC_geoloc()` see 131

- [x] add capability to get geolocation fields at specific image coordinates without loading full HR variable
- [x] add `lazy_loading` option to turn "on" of "off" the `map_block_coords()` mechanism that currently suffer memory leak
- [x] add `load_luts` option to turn "on" of "off" the decoding and rasterization of LUTs.
- [x] prevent the usage of resolution when reading a IW or EW SLC product (this feature is out of scope for `xsar`)

- add land mask suitable for SLC products (compute burst by burst)
- fix re-projection issue with `rasterio==1.3.3`