Mainline GPUI2 UI work (#3079)

This PR mainlines the current state of new GPUI2-based UI from the
`gpui2-ui` branch.

Release Notes:

- N/A

---------

Co-authored-by: Nate Butler <iamnbutler@gmail.com>
Co-authored-by: Piotr Osiewicz <24362066+osiewicz@users.noreply.github.com>
Co-authored-by: Nate <nate@zed.dev>

crates/fs/Cargo.toml

@@ -9,8 +9,6 @@ path = "src/fs.rs"
 
 [dependencies]
 collections = { path = "../collections" }
-gpui = { path = "../gpui" }
-lsp = { path = "../lsp" }
 rope = { path = "../rope" }
 text = { path = "../text" }
 util = { path = "../util" }
@@ -34,8 +32,10 @@ log.workspace = true
 libc = "0.2"
 time.workspace = true
 
+gpui = { path = "../gpui", optional = true}
+
 [dev-dependencies]
 gpui = { path = "../gpui", features = ["test-support"] }
 
 [features]
-test-support = []
+test-support = ["gpui/test-support"]