feat: set up deploys with fly

Signed-off-by: Amogh Lele <amogh@dyte.io>

rel/overlays/bin/server

@@ -0,0 +1,3 @@
+#!/bin/sh
+cd -P -- "$(dirname -- "$0")"
+PHX_SERVER=true exec ./ketbin start

rel/overlays/bin/server.bat

@@ -0,0 +1,2 @@
+set PHX_SERVER=true
+call "%~dp0\ketbin" start