expose all metadata from .nc and .tif files

[lazarusA]

Currently not all metadata is being captured when reading these files. Also, if some properties, such as scale_factor are applied we should be explicit about it.

TODO

• be explicit about the application of properties such as scale_factor or offset.
• consider .nc and .tif.

[danlooo]

See also EarthyScience/RQADeforestation.jl#39
Might also be dangerous to keep properties, e.g. scale_factor after applying them. Similar to concatenatecubes. However, one needs these properties, e.g. to write files with the same scale factor. I'd throw away properties by default and allow the user to explicitly keep them e.g. with open_dataset("foo.tif";keep_properties=true)

[danlooo]

Current behaviour of tif file properties:

• gdalinfo on file : All properties
• xarray.Dataset: No properties
• YAXArrays.Dataset : Only projection as PROJCS string
• xarray.DataArray : Most properties except the already applied ones, e.g.. scale_factor
• YAXArrays.YAXArray : Only missing_value, name, and projection

In addition, there is also:

• optional and less popular band specific properties see also python notebook.
• optional and more popular metadata xml sidecar files, e.g. created by qgis about band statistics, loaded by xarray and ignored by YAXArrays
• xarray treats the band as an additional dimension of the single DataArray band_data, thereby omitting band specific meta data