Switch fully to Rust Livekit (redux) (#27126)

Swift bindings BEGONE

Release Notes:

- Switched from using the Swift LiveKit bindings, to the Rust bindings,
fixing https://github.com/zed-industries/zed/issues/9396, a crash when
leaving a collaboration session, and making Zed easier to build.

---------

Co-authored-by: Conrad Irwin <conrad.irwin@gmail.com>
Co-authored-by: Michael Sloan <michael@zed.dev>

crates/call/src/call.rs

@@ -1,13 +1,5 @@
 pub mod call_settings;
 
-#[cfg(target_os = "macos")]
-mod macos;
+mod call_impl;
 
-#[cfg(target_os = "macos")]
-pub use macos::*;
-
-#[cfg(not(target_os = "macos"))]
-mod cross_platform;
-
-#[cfg(not(target_os = "macos"))]
-pub use cross_platform::*;
+pub use call_impl::*;