GEOMESA-3561 install-dependencies.sh script should exit with non-zero status if a download fails

[cptlobster]

In the functions.sh helper:

downloads+=("(echo >&2 fetching $fname && curl -LsSfo '$tmpfile' '$url' && mv '$tmpfile' '${dest}/${fname}' && chmod 644 '${dest}/${fname}') || echo [ERROR] Failed to fetch $fname")

If the subshell running curl and the associated commands fails, it runs the following echo command. This changes the exit code outputted by the subshell to 0, and as such all commands sent to xargs will return 0. Therefore, any failures in this process will be silently ignored, and the install-dependencies.sh script (and others) will exit as if they succeeded.

This PR saves the exit code from the subshell to a variable and then exits with that code after sending the echo. xargs will then properly exit with code 123 if any of the downloads fail.

[elahrvivaz]

the exit code seems fixed, but now it always prints out [ERROR] Failed to fetch xxx.jar for every single dependency, even when the jar was actually downloaded correctly