Macros need `pw_sys` dependency in the crate that calls the macro

I used the properties!{} macro from another crate that depends on pipewire but not pipewire-sys, and got the following error:

error[E0433]: failed to resolve: use of undeclared crate or module `pw_sys`
   --> src/pipewire_connection.rs:127:66
    |
127 |               core.create_object::<pw::link::Link, _>("link_factory", &pw::properties! {
    |  __________________________________________________________________^
128 | |                 "link.output.node" => link.node_from.to_string()
129 | |             })
    | |_____________^ use of undeclared crate or module `pw_sys`
    |
    = note: this error originates in a macro (in Nightly builds, run with -Z macro-backtrace for more info)

I think we might need to pub use the pipewire_sys crate from the pipewire crate and use it through that instead of depending on it directly in the macro.