debugger: Remove fake adapter and un-gate GDB (#27557)

This is a clean-up PR in anticipation of introduction of Debugger
Registry. I wanna get rid of DebugAdapterKind (or rather, it being an
enum).
Release Notes:

- N/A

---------

Co-authored-by: Anthony Eid <hello@anthonyeid.me>
Co-authored-by: Anthony <anthony@zed.dev>

crates/workspace/Cargo.toml

@@ -35,6 +35,7 @@ client.workspace = true
 clock.workspace = true
 collections.workspace = true
 component.workspace = true
+dap.workspace = true
 db.workspace = true
 derive_more.workspace = true
 fs.workspace = true
@@ -68,6 +69,7 @@ zed_actions.workspace = true
 [dev-dependencies]
 call = { workspace = true, features = ["test-support"] }
 client = { workspace = true, features = ["test-support"] }
+dap = { workspace = true, features = ["test-support"] }
 db = { workspace = true, features = ["test-support"] }
 env_logger.workspace = true
 fs = { workspace = true, features = ["test-support"] }

crates/workspace/src/workspace.rs

@@ -14,6 +14,7 @@ mod toast_layer;
 mod toolbar;
 mod workspace_settings;
 
+use dap::DapRegistry;
 pub use toast_layer::{RunAction, ToastAction, ToastLayer, ToastView};
 
 use anyhow::{anyhow, Context as _, Result};
@@ -637,6 +638,7 @@ pub fn register_serializable_item<I: SerializableItem>(cx: &mut App) {
 
 pub struct AppState {
     pub languages: Arc<LanguageRegistry>,
+    pub debug_adapters: Arc<DapRegistry>,
     pub client: Arc<Client>,
     pub user_store: Entity<UserStore>,
     pub workspace_store: Entity<WorkspaceStore>,
@@ -688,6 +690,7 @@ impl AppState {
 
         let fs = fs::FakeFs::new(cx.background_executor().clone());
         let languages = Arc::new(LanguageRegistry::test(cx.background_executor().clone()));
+        let debug_adapters = Arc::new(DapRegistry::fake());
         let clock = Arc::new(clock::FakeSystemClock::new());
         let http_client = http_client::FakeHttpClient::with_404_response();
         let client = Client::new(clock, http_client.clone(), cx);
@@ -703,6 +706,7 @@ impl AppState {
             client,
             fs,
             languages,
+            debug_adapters,
             user_store,
             workspace_store,
             node_runtime: NodeRuntime::unavailable(),
@@ -1197,6 +1201,7 @@ impl Workspace {
             app_state.node_runtime.clone(),
             app_state.user_store.clone(),
             app_state.languages.clone(),
+            app_state.debug_adapters.clone(),
             app_state.fs.clone(),
             env,
             cx,
@@ -5025,6 +5030,7 @@ impl Workspace {
         window.activate_window();
         let app_state = Arc::new(AppState {
             languages: project.read(cx).languages().clone(),
+            debug_adapters: project.read(cx).debug_adapters().clone(),
             workspace_store,
             client,
             user_store,