use more restrictive mode on temp paths

I get this on each run here:

Notice: /Stage[main]/Nginx::Config/File[/run/nginx/client_body_temp]/mode: mode changed '0700' to '0755'
Notice: /Stage[main]/Nginx::Config/File[/run/nginx/proxy_temp]/mode: mode changed '0700' to '0755'

It seems like nginx and this module have different opinions on the
correct mode for those directories. I believe Nginx is more correct,
and we should therefore follow it.

Note that this might apply to your module only if you have a global
File default resource defined.

Closes: #1272