docker: setup bitcoind docker image in the docker compose yaml file

docker/bitcoind/Dockerfile

@@ -0,0 +1,7 @@
+FROM lightninglabs/bitcoin-core:${BITCOIN_VERSION:-25}
+
+# Copy the start script into the container
+COPY start-bitcoind.sh .
+
+# Set execute permissions for the script
+RUN chmod +x ./start-bitcoind.sh