move Dockerfile an compose to base folder for later support of different packaging

base/docker-compose.yml

@@ -0,0 +1,8 @@
+version: "3"
+services:
+  rust-gtk:
+    image: ghcr.io/13hannes11/gtk4-rs-docker:latest
+    volumes:
+      - ../adwaita-demo:/mnt:z
+    command: /bin/bash -c "cargo build --release"
+