gRPC certificates are world readable #6064
Description
The files ca.pem, ca-key.pem, server.pem, server-key.pem, client.pem and client-key.pem are world readable.
> ls -la *.pem
-rw-r--r-- 1 c-lightning c-lightning 246 Mar 3 23:00 ca-key.pem
-rw-r--r-- 1 c-lightning c-lightning 572 Mar 3 23:00 ca.pem
-rw-r--r-- 1 c-lightning c-lightning 246 Mar 3 23:00 client-key.pem
-rw-r--r-- 1 c-lightning c-lightning 506 Mar 3 23:00 client.pem
-rw-r--r-- 1 c-lightning c-lightning 246 Mar 3 23:00 server-key.pem
-rw-r--r-- 1 c-lightning c-lightning 510 Mar 3 23:00 server.pem