PC: dynamically set PYTHONPATH from real openpilot path (#23322)

* dynamic PYTHONPATH setting based on actual openpilot location

* right above

* fix path

* absolute path all the time

* Revert "absolute path all the time"

This reverts commit c0bc2e08e76bd6c0abd36fa082ee00b4746e62dc.

* Update tools/openpilot_env.sh

Co-authored-by: Willem Melching <willem.melching@gmail.com>

Co-authored-by: Willem Melching <willem.melching@gmail.com>
old-commit-hash: fed7cfeef0

tools/openpilot_env.sh

@@ -1,5 +1,6 @@
 if [ -z "$OPENPILOT_ENV" ]; then
-  export PYTHONPATH="$HOME/openpilot:$PYTHONPATH"
+  OP_ROOT="$(cd "$(dirname "${BASH_SOURCE[0]}")"/.. && pwd)"
+  export PYTHONPATH="$OP_ROOT:$PYTHONPATH"
   export PATH="$HOME/.pyenv/bin:$PATH"
 
   # Pyenv suggests we place the below two lines in .profile before we source