zbus-2.0.0-beta.6

• Add optional D-Bus properties caching to proxies.
• API to monitor changes in properties.
• Implement Stream and Sink on azync::Connection directly. Also implement Sink for &Connection.
• Add ObjectServer::request_name.
• Strongly-typed bus names using the new zbus_names crate. These bus names are now verified.
• Add ConnectionBuilder and azync::ConnectionBuilder, which is the new API to construct connections with custom parameters/configuration.
• Drop _new prefix from Connection::{new_session,new_system}.
• Split ProxyBuilder into async and sync counterparts.
• Expose Address enum in public API. This represents a D-Bus address.
• Generalize ObjectServer::with path error.
• Merge zbus::MessageError into zbus::Error.
• Make AsyncProxy::new async.
• Implement Clone for all proxy types.
• Provide azync::Connection::executor, even when using internal executor.
• Fix infinite recursion on Error's PartialEq implementation.
• Improve signature validation in Message::body.
• Remove unneeded Error::Infallible variant.
• Mark Error enum non-exhaustive.
• Dependencies added:
  • async-recursion
  • zbus_names
• Other fixes and improvements.