jibri: add check for /dev/shm size

If the container was staryed without a /dev/shm of at least 2GB
(defaults to 6MB in Docker) Chrome will behave erratically or crash.

Catch this with a tiny binary and make the container fail to start.

Ref: https://github.com/jitsi/docker-jitsi-meet/issues/1653

jibri/rootfs/etc/cont-init.d/10-config

@@ -1,5 +1,11 @@
 #!/usr/bin/with-contenv bash
 
+# Check if /dev/shm is large enough (2GB at least)
+if ! shm-check; then
+    echo "/dev/shm must be at least 2GB in size"
+    exit 1
+fi
+
 if [[ -z $JIBRI_RECORDER_PASSWORD || -z $JIBRI_XMPP_PASSWORD ]]; then
     echo 'FATAL ERROR: Jibri recorder password and auth password must be set'
     exit 1