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/symfony/polyfill-php72/bootstrap.php

@@ -0,0 +1,57 @@
+<?php
+
+/*
+ * This file is part of the Symfony package.
+ *
+ * (c) Fabien Potencier <fabien@symfony.com>
+ *
+ * For the full copyright and license information, please view the LICENSE
+ * file that was distributed with this source code.
+ */
+
+use Symfony\Polyfill\Php72 as p;
+
+if (\PHP_VERSION_ID >= 70200) {
+    return;
+}
+
+if (!defined('PHP_FLOAT_DIG')) {
+    define('PHP_FLOAT_DIG', 15);
+}
+if (!defined('PHP_FLOAT_EPSILON')) {
+    define('PHP_FLOAT_EPSILON', 2.2204460492503E-16);
+}
+if (!defined('PHP_FLOAT_MIN')) {
+    define('PHP_FLOAT_MIN', 2.2250738585072E-308);
+}
+if (!defined('PHP_FLOAT_MAX')) {
+    define('PHP_FLOAT_MAX', 1.7976931348623157E+308);
+}
+if (!defined('PHP_OS_FAMILY')) {
+    define('PHP_OS_FAMILY', p\Php72::php_os_family());
+}
+
+if ('\\' === \DIRECTORY_SEPARATOR && !function_exists('sapi_windows_vt100_support')) {
+    function sapi_windows_vt100_support($stream, $enable = null) { return p\Php72::sapi_windows_vt100_support($stream, $enable); }
+}
+if (!function_exists('stream_isatty')) {
+    function stream_isatty($stream) { return p\Php72::stream_isatty($stream); }
+}
+if (!function_exists('utf8_encode')) {
+    function utf8_encode($string) { return p\Php72::utf8_encode($string); }
+}
+if (!function_exists('utf8_decode')) {
+    function utf8_decode($string) { return p\Php72::utf8_decode($string); }
+}
+if (!function_exists('spl_object_id')) {
+    function spl_object_id($object) { return p\Php72::spl_object_id($object); }
+}
+if (!function_exists('mb_ord')) {
+    function mb_ord($string, $encoding = null) { return p\Php72::mb_ord($string, $encoding); }
+}
+if (!function_exists('mb_chr')) {
+    function mb_chr($codepoint, $encoding = null) { return p\Php72::mb_chr($codepoint, $encoding); }
+}
+if (!function_exists('mb_scrub')) {
+    function mb_scrub($string, $encoding = null) { $encoding = null === $encoding ? mb_internal_encoding() : $encoding; return mb_convert_encoding($string, $encoding, $encoding); }
+}