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/public/js/tinymce/plugins/codesample/css/prism.css

@@ -0,0 +1,138 @@
+/* http://prismjs.com/download.html?themes=prism&languages=markup+css+clike+javascript */
+/**
+ * prism.js default theme for JavaScript, CSS and HTML
+ * Based on dabblet (http://dabblet.com)
+ * @author Lea Verou
+ */
+
+code[class*="language-"],
+pre[class*="language-"] {
+  color: black;
+  text-shadow: 0 1px white;
+  font-family: Consolas, Monaco, 'Andale Mono', 'Ubuntu Mono', monospace;
+  direction: ltr;
+  text-align: left;
+  white-space: pre;
+  word-spacing: normal;
+  word-break: normal;
+  word-wrap: normal;
+  line-height: 1.5;
+
+  -moz-tab-size: 4;
+  -o-tab-size: 4;
+  tab-size: 4;
+
+  -webkit-hyphens: none;
+  -moz-hyphens: none;
+  -ms-hyphens: none;
+  hyphens: none;
+}
+
+pre[class*="language-"]::-moz-selection, pre[class*="language-"] ::-moz-selection,
+code[class*="language-"]::-moz-selection, code[class*="language-"] ::-moz-selection {
+  text-shadow: none;
+  background: #b3d4fc;
+}
+
+pre[class*="language-"]::selection, pre[class*="language-"] ::selection,
+code[class*="language-"]::selection, code[class*="language-"] ::selection {
+  text-shadow: none;
+  background: #b3d4fc;
+}
+
+@media print {
+  code[class*="language-"],
+  pre[class*="language-"] {
+    text-shadow: none;
+  }
+}
+
+/* Code blocks */
+pre[class*="language-"] {
+  padding: 1em;
+  margin: .5em 0;
+  overflow: auto;
+}
+
+:not(pre) > code[class*="language-"],
+pre[class*="language-"] {
+  background: #f5f2f0;
+}
+
+/* Inline code */
+:not(pre) > code[class*="language-"] {
+  padding: .1em;
+  border-radius: .3em;
+}
+
+.token.comment,
+.token.prolog,
+.token.doctype,
+.token.cdata {
+  color: slategray;
+}
+
+.token.punctuation {
+  color: #999;
+}
+
+.namespace {
+  opacity: .7;
+}
+
+.token.property,
+.token.tag,
+.token.boolean,
+.token.number,
+.token.constant,
+.token.symbol,
+.token.deleted {
+  color: #905;
+}
+
+.token.selector,
+.token.attr-name,
+.token.string,
+.token.char,
+.token.builtin,
+.token.inserted {
+  color: #690;
+}
+
+.token.operator,
+.token.entity,
+.token.url,
+.language-css .token.string,
+.style .token.string {
+  color: #a67f59;
+  background: hsla(0, 0%, 100%, .5);
+}
+
+.token.atrule,
+.token.attr-value,
+.token.keyword {
+  color: #07a;
+}
+
+.token.function {
+  color: #DD4A68;
+}
+
+.token.regex,
+.token.important,
+.token.variable {
+  color: #e90;
+}
+
+.token.important,
+.token.bold {
+  font-weight: bold;
+}
+.token.italic {
+  font-style: italic;
+}
+
+.token.entity {
+  cursor: help;
+}
+