Accept other variables in the docker image

[mzfr]

So I realized with the current docker image we couldn't give auth or authfile as inputs because in the entrypoint.sh we aren't looking for those environment variables (even if they are set).

We should have a feature where we allow passing extra(supported) environment variables to the docker image.

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Will probably need to update the bash script to check if certain variables are set or not if they are to use them in the su-exec command.