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/league/commonmark/src/Parser/InlineParserContext.php

@@ -0,0 +1,120 @@
+<?php
+
+declare(strict_types=1);
+
+/*
+ * This file is part of the league/commonmark package.
+ *
+ * (c) Colin O'Dell <colinodell@gmail.com>
+ *
+ * Original code based on the CommonMark JS reference parser (https://bitly.com/commonmark-js)
+ *  - (c) John MacFarlane
+ *
+ * For the full copyright and license information, please view the LICENSE
+ * file that was distributed with this source code.
+ */
+
+namespace League\CommonMark\Parser;
+
+use League\CommonMark\Delimiter\DelimiterStack;
+use League\CommonMark\Node\Block\AbstractBlock;
+use League\CommonMark\Reference\ReferenceMapInterface;
+
+final class InlineParserContext
+{
+    /** @psalm-readonly */
+    private AbstractBlock $container;
+
+    /** @psalm-readonly */
+    private ReferenceMapInterface $referenceMap;
+
+    /** @psalm-readonly */
+    private Cursor $cursor;
+
+    /** @psalm-readonly */
+    private DelimiterStack $delimiterStack;
+
+    /**
+     * @var string[]
+     * @psalm-var non-empty-array<string>
+     *
+     * @psalm-readonly-allow-private-mutation
+     */
+    private array $matches;
+
+    public function __construct(Cursor $contents, AbstractBlock $container, ReferenceMapInterface $referenceMap)
+    {
+        $this->referenceMap   = $referenceMap;
+        $this->container      = $container;
+        $this->cursor         = $contents;
+        $this->delimiterStack = new DelimiterStack();
+    }
+
+    public function getContainer(): AbstractBlock
+    {
+        return $this->container;
+    }
+
+    public function getReferenceMap(): ReferenceMapInterface
+    {
+        return $this->referenceMap;
+    }
+
+    public function getCursor(): Cursor
+    {
+        return $this->cursor;
+    }
+
+    public function getDelimiterStack(): DelimiterStack
+    {
+        return $this->delimiterStack;
+    }
+
+    /**
+     * @return string The full text that matched the InlineParserMatch definition
+     */
+    public function getFullMatch(): string
+    {
+        return $this->matches[0];
+    }
+
+    /**
+     * @return int The length of the full match (in characters, not bytes)
+     */
+    public function getFullMatchLength(): int
+    {
+        return \mb_strlen($this->matches[0], 'UTF-8');
+    }
+
+    /**
+     * @return string[] Similar to preg_match(), index 0 will contain the full match, and any other array elements will be captured sub-matches
+     *
+     * @psalm-return non-empty-array<string>
+     */
+    public function getMatches(): array
+    {
+        return $this->matches;
+    }
+
+    /**
+     * @return string[]
+     */
+    public function getSubMatches(): array
+    {
+        return \array_slice($this->matches, 1);
+    }
+
+    /**
+     * @param string[] $matches
+     *
+     * @psalm-param non-empty-array<string> $matches
+     */
+    public function withMatches(array $matches): InlineParserContext
+    {
+        $ctx = clone $this;
+
+        $ctx->matches = $matches;
+
+        return $ctx;
+    }
+}