Moved to zopefoundation/ZServer@ee3cb3c7576df0de96d0fe96fbdc7912efed3049.

Also adjust some deprecation warnings to refer to Zope 5.0.

Moved to zopefoundation/ZServer@23f8ec7b39c9558bbce83e66b700b8c26693255a.

The locking concept is generally useful and used outside of
the webdav context.

It will be needed by AccessControl 4.0

This reduces the supported `zope.conf` directives when run under WSGI.
In particular directives related to ZServer and zopectl and those
changing sys.path are not supported.

Most code related to temp_folder was already removed in 4.0a1.

If Zope is run as a WSGI app, this avoids doing any ZServer related work.

This avoids various import dependencies between the Startup code
and ZServer/webdav.