Sync engine (#298)

Fixes #261

plug-api/plugos-syscall/mod.ts

@@ -1,6 +1,7 @@
 export * as asset from "./asset.ts";
 export * as events from "./event.ts";
-export * as fs from "./fs.ts";
+// export * as fs from "./fs.ts";
+export { LocalFileSystem } from "./fs.ts";
 export * as sandbox from "./sandbox.ts";
 export * as fulltext from "./fulltext.ts";
 export * as shell from "./shell.ts";