GHW for building and publishing docker images (#1391)

* add ghw and scripts for docker image deployment

* debug

* add permissions for content

* fix path to the bin folder

* add tags

* rename env

* fix path to docker file

* make polkadot-parachain executable

* fix typo

* fix more typos

* test

* revert back  use of  working directory

* mke bin executable in the artifacts folder

* use cd instead of working directory

* change path to cash

* fix path to cash

* change cache key

* delete old flows

* addressed PR comments

* fix path

* reorg docker files

docker/scripts/entrypoint.sh

@@ -0,0 +1,18 @@
+#!/usr/bin/env bash
+
+# Sanity check
+if [ -z "$BINARY" ]
+then
+    echo "BINARY ENV not defined, this should never be the case. Aborting..."
+    exit 1
+fi
+
+# If the user built the image with multiple binaries,
+# we consider the first one to be the canonical one
+# To start with another binary, the user can either:
+#  - use the --entrypoint option
+#  - pass the ENV BINARY with a single binary
+IFS=',' read -r -a BINARIES <<< "$BINARY"
+BIN0=${BINARIES[0]}
+echo "Starting binary $BIN0"
+$BIN0 $@