Simplify livekit config so that cargo check Just Works (#21661)

Supersedes https://github.com/zed-industries/zed/pull/21653

This enables us to use `cargo test -p workspace` on macOS and Linux.

Note that the line diffs in `shared_screen.rs` are spurious, I just
re-ordered the `macos` and `cross-platform` modules to match the order
in the call crate.

Release Notes:

- N/A

script/check-rust-livekit-macos

@@ -0,0 +1,19 @@
+#!/bin/bash
+
+
+set -exuo pipefail
+
+git apply script/patches/use-cross-platform-livekit.patch
+
+# Re-enable error skipping for this check, so that we can unapply the patch
+set +e
+
+cargo check -p workspace
+exit_code=$?
+
+# Disable error skipping again
+set -e
+
+git apply -R script/patches/use-cross-platform-livekit.patch
+
+exit "$exit_code"

script/patches/use-cross-platform-livekit.patch

@@ -0,0 +1,59 @@
+diff --git a/crates/call/Cargo.toml b/crates/call/Cargo.toml
+index 9ba10e56ba..bb69440691 100644
+--- a/crates/call/Cargo.toml
++++ b/crates/call/Cargo.toml
+@@ -41,10 +41,10 @@ serde_derive.workspace = true
+ settings.workspace = true
+ util.workspace = true
+ 
+-[target.'cfg(target_os = "macos")'.dependencies]
++[target.'cfg(any())'.dependencies]
+ livekit_client_macos = { workspace = true }
+ 
+-[target.'cfg(not(target_os = "macos"))'.dependencies]
++[target.'cfg(all())'.dependencies]
+ livekit_client = { workspace = true }
+ 
+ [dev-dependencies]
+diff --git a/crates/call/src/call.rs b/crates/call/src/call.rs
+index 5e212d35b7..a8f9e8f43e 100644
+--- a/crates/call/src/call.rs
++++ b/crates/call/src/call.rs
+@@ -1,13 +1,13 @@
+ pub mod call_settings;
+ 
+-#[cfg(target_os = "macos")]
++#[cfg(any())]
+ mod macos;
+ 
+-#[cfg(target_os = "macos")]
++#[cfg(any())]
+ pub use macos::*;
+ 
+-#[cfg(not(target_os = "macos"))]
++#[cfg(all())]
+ mod cross_platform;
+ 
+-#[cfg(not(target_os = "macos"))]
++#[cfg(all())]
+ pub use cross_platform::*;
+diff --git a/crates/workspace/src/shared_screen.rs b/crates/workspace/src/shared_screen.rs
+index 1d17cfa145..f845234987 100644
+--- a/crates/workspace/src/shared_screen.rs
++++ b/crates/workspace/src/shared_screen.rs
+@@ -1,11 +1,11 @@
+-#[cfg(target_os = "macos")]
++#[cfg(any())]
+ mod macos;
+ 
+-#[cfg(target_os = "macos")]
++#[cfg(any())]
+ pub use macos::*;
+ 
+-#[cfg(not(target_os = "macos"))]
++#[cfg(all())]
+ mod cross_platform;
+ 
+-#[cfg(not(target_os = "macos"))]
++#[cfg(all())]
+ pub use cross_platform::*;