Handle numerical metadata fields stored as strings in GeoTIFFS

[mcvittal]

This change allows for GeoTIFFS that have numerical metadata stored as string (and numerical arrays stored as space delimited strings) to be read in properly by SNAP.

[marpet]

Now, I have seen the issue in JIRA (https://senbox.atlassian.net/browse/SNAP-1500) and that it can be read by GDAL. But still, it doesn't follow the specs. Who is providing this data? GDAL can read it because of the GDALMetadata tag contained in the attributes, I guess.

[marpet]

I've checked the file you have provided. I can read it without the modifications. The GDAL GEoTiff reader is used in SNAP because it is a COG file. Even when I explicitly used from code the GeoTiffReader it works. When debugging I can see that the attribute fields are doubles, respectively ints.

[CLAassistant]

All committers have signed the CLA.

[lveci]

Closing this old PR since it is no longer relevant