Complete redo of content indexing and querying (#517)

Complete redo of data store
Introduces live queries and live templates

common/syscalls/handlebars.ts

@@ -0,0 +1,23 @@
+import { SysCallMapping } from "../../plugos/system.ts";
+import { handlebarHelpers } from "./handlebar_helpers.ts";
+import Handlebars from "handlebars";
+
+export function handlebarsSyscalls(): SysCallMapping {
+  return {
+    "handlebars.renderTemplate": (
+      _ctx,
+      template: string,
+      obj: any,
+      globals: Record<string, any> = {},
+    ): string => {
+      const templateFn = Handlebars.compile(
+        template,
+        { noEscape: true },
+      );
+      return templateFn(obj, {
+        helpers: handlebarHelpers(),
+        data: globals,
+      });
+    },
+  };
+}