Build modified streamline images

The official image from streamline does not currently work for the arm64
platform. As a temporary measure, the source code and docker build scripts
have been lifted from the official images and are used to build locally.

Some additional modifications are made to reduce overall image size, these
are documented in docker/README.md

docker/streamline-src/vendor/bin/wkhtmltopdf-amd64

@@ -0,0 +1,37 @@
+#!/usr/bin/env sh
+
+# Support bash to support `source` with fallback on $0 if this does not run with bash
+# https://stackoverflow.com/a/35006505/6512
+selfArg="$BASH_SOURCE"
+if [ -z "$selfArg" ]; then
+    selfArg="$0"
+fi
+
+self=$(realpath $selfArg 2> /dev/null)
+if [ -z "$self" ]; then
+    self="$selfArg"
+fi
+
+dir=$(cd "${self%[/\\]*}" > /dev/null; cd '../h4cc/wkhtmltopdf-amd64/bin' && pwd)
+
+if [ -d /proc/cygdrive ]; then
+    case $(which php) in
+        $(readlink -n /proc/cygdrive)/*)
+            # We are in Cygwin using Windows php, so the path must be translated
+            dir=$(cygpath -m "$dir");
+            ;;
+    esac
+fi
+
+export COMPOSER_RUNTIME_BIN_DIR="$(cd "${self%[/\\]*}" > /dev/null; pwd)"
+
+# If bash is sourcing this file, we have to source the target as well
+bashSource="$BASH_SOURCE"
+if [ -n "$bashSource" ]; then
+    if [ "$bashSource" != "$0" ]; then
+        source "${dir}/wkhtmltopdf-amd64" "$@"
+        return
+    fi
+fi
+
+"${dir}/wkhtmltopdf-amd64" "$@"