refactor: extract inlined shell script in action to own file

[okize]

I tried a couple other things before going with environment variables to pass args into the shell script.

using positional arguments didn't work because in order for the postfix to work, the prefix can't be set and passing an empty string didn't work, so whatever was set for the postfix argument would end up as the prefix.

I tried using single char flags (ie. -f for filename) like this:

bash ${GITHUB_ACTION_PATH}/parse_tool_versions.sh -f ${{ inputs.filename }} -u ${{ inputs.uppercase }} -p ${{ inputs.prefix }} -x ${{ inputs.postfix }} >> $GITHUB_ENV

and in the script:

+while getopts "f:u:p:x" option; do
+case "$option" in
+f) filename=${OPTARG};;
+u) uppercase=${OPTARG};;
+p) prefix=${OPTARG};;
+x) postfix=${OPTARG};;
+*) echo "Invalid option";;
+esac
+done

but faced the same problem... if inputs.prefix was unset, -x would end up being the value passed into -p and so you'd end up with _X_NODEJS etc.

there's probably something better than environment variables but this works