Massive restructure of plugin API

plug-api/silverbullet-syscall/clientStore.ts

@@ -0,0 +1,13 @@
+import { syscall } from "./syscall.ts";
+
+export function set(key: string, value: any): Promise<void> {
+  return syscall("clientStore.set", key, value);
+}
+
+export function get(key: string): Promise<any> {
+  return syscall("clientStore.get", key);
+}
+
+export function del(key: string): Promise<void> {
+  return syscall("clientStore.delete", key);
+}