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/barryvdh/laravel-snappy/src/Facades/SnappyPdf.php

@@ -0,0 +1,40 @@
+<?php
+namespace Barryvdh\Snappy\Facades;
+
+use Illuminate\Support\Facades\Facade as BaseFacade;
+use Barryvdh\Snappy\PdfFaker;
+
+
+/**
+ * @method static \Barryvdh\Snappy\PdfWrapper setPaper($paper, $orientation = 'portrait')
+ * @method static \Barryvdh\Snappy\PdfWrapper setWarnings($warnings)
+ * @method static \Barryvdh\Snappy\PdfWrapper setOptions(array $options)
+ * @method static \Barryvdh\Snappy\PdfWrapper loadView($view, $data = array(), $mergeData = array(), $encoding = null)
+ * @method static \Barryvdh\Snappy\PdfWrapper loadHTML($string, $encoding = null)
+ * @method static \Barryvdh\Snappy\PdfWrapper loadFile($file)
+ * @method static string output($options = [])
+ * @method static \Barryvdh\Snappy\PdfWrapper save()
+ * @method static \Illuminate\Http\Response download($filename = 'document.pdf')
+ * @method static \Illuminate\Http\Response inline($filename = 'document.pdf')
+ *
+ */
+class SnappyPdf extends BaseFacade {
+
+    /**
+     * Get the registered name of the component.
+     *
+     * @return string
+     */
+    protected static function getFacadeAccessor() { return 'snappy.pdf.wrapper'; }
+
+    /**
+     * Replace the bound instance with a fake.
+     *
+     * @return void
+     */
+    public static function fake()
+    {
+        static::swap(new PdfFaker(app('snappy.pdf')));
+    }
+
+}