Issue #1083366 by jmcclelland, helmo, EugenMayer, cschaub, gmania: Fixed Make the spokes authoritative for files/ and private/ directories.

This reverts commit 6537cb81.

because of #955018, setting site_offline doesn't propagate to the context so we need to use a variable already defined, we chose site_enabled

because of #955018, setting site_offline doesn't propagate to the context so we need to use a variable already defined, we chose site_enabled

More fixes relating to #907248 .. ensure that the migrated site returns the new values from the config.

Migration between servers works. It now deletes the vhost file first, and if it gets recreated that's cool.

the singular filesystem object now.

Sync is now a method of the server class, with a helpful method associated
to the services that redirect to the service's server.

Sort of fix site import, which also verifies now. Introduce d()->site_path instead of concatenating everywhere.

a separate task.

had to make a nasty hack to step around drush internals because site aliases
put stuff in the options context that dont come from the command line options.

Removed the provision_service function, and introduce service handler subscriptions in the environment objects.

Instead of provision_service('type') you now use d()->service('type') to access the service object.
The context object returned by d() now manages which context object's service to return, based
on the internally managed subscriptions.

Committed drumm's cleanup patch that takes care of permission checks inside the config writing code,
and some other fixes to get install etc. working again

This gets rid of the path function, and introduces method chaining for the file service, which results in far cleaner code.