Add Google Shell Style Guide documentation to uninstall-common.sh (#446)

* Initial plan

* Add comprehensive Google Shell Style Guide documentation to uninstall-common.sh

Co-authored-by: crramirez <8397379+crramirez@users.noreply.github.com>

* Update pengwin-setup.d/uninstall/uninstall-common.sh

* Update pengwin-setup.d/uninstall/uninstall-common.sh

Co-authored-by: Copilot <175728472+Copilot@users.noreply.github.com>

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Co-authored-by: copilot-swe-agent[bot] <198982749+Copilot@users.noreply.github.com>
Co-authored-by: crramirez <8397379+crramirez@users.noreply.github.com>
Co-authored-by: Carlos Rafael Ramirez <crramirez@users.noreply.github.com>
Co-authored-by: Copilot <175728472+Copilot@users.noreply.github.com>

Author: 3 people