Add GitHub Docker action for testing UDP and HTTP file transfers

The Dockerfile works when run locally. The GitHub action
plumbing may or not work in this state.

.github/actions/test-transfer-udp-http/Dockerfile

@@ -0,0 +1,8 @@
+# Container image that runs your code
+FROM rust:latest
+
+# Copies your code file from your action repository to the filesystem path `/` of the container
+COPY entrypoint.sh /entrypoint.sh
+
+# Code file to execute when the docker container starts up (`entrypoint.sh`)
+ENTRYPOINT ["/entrypoint.sh"]