Fixes #8748 - Allow per-module enabling of http(s)

Defaults to http=off and https=on for all except the templates module which is the reverse. Not added to RootPlugin as that should always be on anyway.

I'm wondering if it makes sense to do something more condensed like `:enabled = http|https|true(both)|false(none)` ?
thats a good idea, but how would I know which setting file to check (i.e whats the plugin name)? as far as i can see, http_rackup_path doesn't care what the plugin namespace is, and while I can guess it from the filename (File.expand_path... has /modules/dhcp/ in it for example) the namespace isn't consisent (Proxy::TFTP::Plugin vs Proxy::DhcpPlugin for example)