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/nikic/php-parser/lib/PhpParser/Parser.php

@@ -0,0 +1,24 @@
+<?php declare(strict_types=1);
+
+namespace PhpParser;
+
+interface Parser {
+    /**
+     * Parses PHP code into a node tree.
+     *
+     * @param string $code The source code to parse
+     * @param ErrorHandler|null $errorHandler Error handler to use for lexer/parser errors, defaults
+     *                                        to ErrorHandler\Throwing.
+     *
+     * @return Node\Stmt[]|null Array of statements (or null non-throwing error handler is used and
+     *                          the parser was unable to recover from an error).
+     */
+    public function parse(string $code, ?ErrorHandler $errorHandler = null): ?array;
+
+    /**
+     * Return tokens for the last parse.
+     *
+     * @return Token[]
+     */
+    public function getTokens(): array;
+}