Add generic Kubectl binary download script for all Linux distributions

[kevydotvinu]

Changes

Kubectl binary download script modification has been done to accommodate support for all Linux distributions. It is relatively short, requires no sudo and should run on most distros just fine.

Submitter Checklist

• Includes tests if functionality changed/was added
• Includes docs if changes are user-facing
• Set a kind label on this PR
• Release notes block has been filled in, or marked NONE

Release Notes

NONE

[coreydaley]

I would rather see ${HOME}/bin as the first location to be checked since this is not an official installation script.

[HeavyWombat]

@kevydotvinu I think it is a good point that @coreydaley brought up here. Maybe you can change this piece here and the one in shipwright-io/build#819 to this one:

# Find a suitable install location
for CANDIDATE in "$HOME/bin" "/usr/local/bin" "/usr/bin"; do
  if [[ -w $CANDIDATE ]] && grep -q "$CANDIDATE" <<<"$PATH"; then
    TARGET_DIR="$CANDIDATE"
    break
  fi
done

# Bail out in case no suitable location could be found
if [[ -z ${TARGET_DIR:-} ]]; then
  echo -e "Unable to determine a writable install location. Make sure that you have write access to either \\033[1m/usr/local/bin\\033[0m or \\033[1m${HOME}/bin\\033[0m and that is in your PATH."
  exit 1
fi

I tried it out in my repository and this should be better to read and better to maintain in terms of the order.

[kevydotvinu]

I have made the suggested changes in both places. Thanks, @HeavyWombat @coreydaley.

[HeavyWombat]

/lgtm

[HeavyWombat]

/approve

[openshift-ci]

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