feat: support multiple shells in the setup script

[rachwalk]

Purpose

While bash is the most popular shell by far, many users prefer to use zsh on their setups for improved interactivity. ROS2 supports setup scripts for bash, zsh, and sh so RAI should provide users with ability to set up either of the three out of the box.

Proposed Changes

Adds support multiple shells in the setup script

Issues

N/A

Testing

the script has been tested by the following procedure:

chsh [shell_name]
source ./setup_shell.sh
echo $PYTHON_PATH

The setup has worked correctly for bash, zsh, and sh.