feat: PlantUML markdown module (#1066)

* initial plantuml work

* got plantuml rendering working

* fix: added plantuml module config order

server/modules/rendering/markdown-plantuml/renderer.js

@@ -0,0 +1,16 @@
+const mdPlantUml = require('markdown-it-plantuml')
+
+// ------------------------------------
+// Markdown - PlantUML Preprocessor
+// ------------------------------------
+
+module.exports = {
+  init (md, conf) {
+    md.use(mdPlantUml, {
+      openMarker: conf.openMarker,
+      closeMarker: conf.closeMarker,
+      imageFormat: conf.imageFormat,
+      server: conf.server
+    })
+  }
+}