9: Add POC for actor templates

- This commit adds a proof-of-concept for retrieving actor template
  types. These are actors using the `worldbuilding.isTemplate` flag set
  to true. If there are multiple actors with that flag set to true,
  clicking the create actor button will pull up a prompt to choose from
  one of those types, which will then create an actor by duplicating
  the template actor's data. The flag will be unset on the new actor.

module/templates.js

@@ -0,0 +1,16 @@
+/**
+ * Define a set of template paths to pre-load
+ * Pre-loaded templates are compiled and cached for fast access when rendering
+ * @return {Promise}
+ */
+export const preloadHandlebarsTemplates = async function() {
+
+  // Define template paths to load
+  const templatePaths = [
+    // Attribute list partial.
+    "systems/worldbuilding/templates/parts/sheet-attributes.html"
+  ];
+
+  // Load the template parts
+  return loadTemplates(templatePaths);
+};