Add GET endpoints for getting the state of the finder

* GET / (or GET /current)
* GET /query

src/options.go

@@ -113,7 +113,7 @@ const usage = `usage: fzf [options]
     --read0                Read input delimited by ASCII NUL characters
     --print0               Print output delimited by ASCII NUL characters
     --sync                 Synchronous search for multi-staged filtering
-    --listen=HTTP_PORT     Start HTTP server to receive actions (POST /)
+    --listen=HTTP_PORT     Start HTTP server to receive actions
     --version              Display version information and exit
 
   Environment variables