fix configurable SSH key path in rstudio helper script

Agent-Logs-Url: https://github.com/codez0mb1e/data-engineer-server/sessions/89c9736f-7e39-4d48-81cb-8e5d202dfe25

Co-authored-by: codez0mb1e <1914621+codez0mb1e@users.noreply.github.com>

Author: Copilot

rstudio-server/server/rstudio_docker.sh

@@ -8,13 +8,14 @@
 USR="<username>"
 PWD="<your-very-secure-pwd-here>"
 HOST="<host>"
+SSH_KEY_PATH="$HOME/.ssh/<path-to-private-key>"
 
 docker pull rocker/tidyverse:4.5
 docker run -d -p 8787:8787 -e PASSWORD=$PWD -v /home/$USR/apps/:/home/rstudio/ --name rserver rocker/tidyverse:4.5
 
 docker start -i rserver
 
-ssh -i ~/.ssh/$USR -N -L 8787:localhost:8787 $USR@$HOST
+ssh -i "$SSH_KEY_PATH" -N -L 8787:localhost:8787 "${USR}@${HOST}"
 # Open rstudio http://localhost:8787/