Complete redo of content indexing and querying (#517)

Complete redo of data store
Introduces live queries and live templates

plug-api/silverbullet-syscall/clientStore.ts

@@ -1,5 +1,10 @@
 import { syscall } from "./syscall.ts";
 
+/**
+ * Implements a very simple (string) key value store for the client.
+ * Generally should only be used to set some client-specific states, such as preferences.
+ */
+
 export function set(key: string, value: any): Promise<void> {
   return syscall("clientStore.set", key, value);
 }