devcontainer improvements (#31650)

.devcontainer/Dockerfile

@@ -1,6 +1,6 @@
 FROM ghcr.io/commaai/openpilot-base:latest
 
-RUN apt update && apt install -y vim net-tools usbutils htop ripgrep tmux wget mesa-utils xvfb libxtst6 libxv1 libglu1-mesa libegl1-mesa
+RUN apt update && apt install -y vim net-tools usbutils htop ripgrep tmux wget mesa-utils xvfb libxtst6 libxv1 libglu1-mesa libegl1-mesa gdb
 RUN pip install ipython jupyter jupyterlab
 
 RUN cd /tmp && \

.devcontainer/devcontainer.json

@@ -18,7 +18,6 @@
     "--volume=${localWorkspaceFolder}/.devcontainer/.host/.Xauthority:/home/batman/.Xauthority",
     "--volume=${localEnv:HOME}/.comma:/home/batman/.comma",
     "--volume=/tmp/comma_download_cache:/tmp/comma_download_cache",
-    "--volume=/tmp/devcontainer_scons_cache:/tmp/scons_cache",
     "--shm-size=1G",
     "--add-host=host.docker.internal:host-gateway", // required to use host.docker.internal on linux
     "--publish=0.0.0.0:8070-8079:8070-8079"  // body ZMQ services
@@ -43,5 +42,8 @@
         "lharri73.dbc"
       ]
     }
-  }
+  },
+  "mounts": [
+    "type=volume,source=scons_cache,target=/tmp/scons_cache"
+  ]
 }