Upgrade to SNAP 9.0.0 (#16)

[thierryweo]

Hello, I upgraded SNAP to 9.0.0 as in this ticket #16

There were a few changes necessary

1. /usr/local/snap/bin/snap --nosplash --nogui --modules --update-all https://github.com/mundialis/esa-snap/compare/master...thierryweo:esa-snap:master#diff-dd2c0eb6ea5cfc6c4bd4eac30934e2d5746747af48fef6da689e85b752f39557L72 does not terminate. Fix is to write a short shell command to look for a special line and then terminate the process (update.sh)
2. /usr/local/snap/bin/snappy-conf /usr/bin/python3 command does no terminate so same as in point 1. wait for last line and terminate java process
3. openjdk8is not necessay in final Docker image as it is already baked in the base image

Test Image is pushed here to test https://hub.docker.com/repository/docker/thierrydoc/esa-snap/general I am not 100% sure everything is setup correctly:

1. Following message appears

INFO: org.esa.s2tbx.dataio.gdal.GDALVersion: GDAL not found on system. Internal GDAL 3.2.1 from distribution will be used. (f0)
INFO: org.esa.s2tbx.dataio.gdal.GDALVersion: Internal GDAL 3.2.1 set to be used by SNAP.
Native library load failed.
java.lang.UnsatisfiedLinkError: /root/.snap/auxdata/gdal/gdal-3-2-1/lib/jni/libgdalalljni.so: Error loading shared library ld-linux-x86-64.so.2: No such file or directory (needed by /root/.snap/auxdata/gdal/gdal-3-2-1/lib/jni/libgdal.so)
SEVERE: org.esa.s2tbx.dataio.gdal.GDALLoader: Failed to initialize GDAL native drivers. GDAL readers and writers were disabled.java.lang.reflect.InvocationTargetException
INFO: org.esa.snap.core.util.EngineVersionCheckActivator: Please check regularly for new updates for the best SNAP experience.```


Please let me know if there are problems I will look into them happily