Add workflow that runs simple test with the engine present

utils/test/run.sh

@@ -0,0 +1,19 @@
+#!/bin/bash -e
+world=$(mktemp -d)
+trap 'rm -rf "$world" || :' EXIT
+
+[ -f game.conf ] || { echo "Must be run in game root folder." >&2; exit 1; }
+
+cp -v utils/test/world.mt "$world/"
+chmod -R a+rwX "$world" # needed because server runs as unprivileged user inside container
+
+vol=(
+	-v "$PWD/utils/test/minetest.conf":/etc/minetest/minetest.conf
+	--tmpfs /var/lib/minetest/.minetest
+	-v "$PWD":/var/lib/minetest/.minetest/games/minetest_game
+	-v "$world":/var/lib/minetest/.minetest/world
+)
+[ -z "$DOCKER_IMAGE" ] && DOCKER_IMAGE="ghcr.io/minetest/minetest:master"
+docker run --rm -i "${vol[@]}" "$DOCKER_IMAGE"
+
+exit 0