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/debugger_ui/src/debugger_ui.rs

@@ -0,0 +1,122 @@
+use dap::debugger_settings::DebuggerSettings;
+use debugger_panel::{DebugPanel, ToggleFocus};
+use feature_flags::{Debugger, FeatureFlagViewExt};
+use gpui::App;
+use session::DebugSession;
+use settings::Settings;
+use workspace::{
+    Pause, Restart, ShutdownDebugAdapters, StepBack, StepInto, StepOver, Stop,
+    ToggleIgnoreBreakpoints, Workspace,
+};
+
+pub mod attach_modal;
+pub mod debugger_panel;
+pub mod session;
+
+#[cfg(test)]
+mod tests;
+
+pub fn init(cx: &mut App) {
+    DebuggerSettings::register(cx);
+    workspace::FollowableViewRegistry::register::<DebugSession>(cx);
+
+    cx.observe_new(|_: &mut Workspace, window, cx| {
+        let Some(window) = window else {
+            return;
+        };
+
+        cx.when_flag_enabled::<Debugger>(window, |workspace, _, _| {
+            workspace
+                .register_action(|workspace, _: &ToggleFocus, window, cx| {
+                    workspace.toggle_panel_focus::<DebugPanel>(window, cx);
+                })
+                .register_action(|workspace, _: &Pause, _, cx| {
+                    let debug_panel = workspace.panel::<DebugPanel>(cx).unwrap();
+
+                    if let Some(active_item) = debug_panel.read_with(cx, |panel, cx| {
+                        panel
+                            .active_session(cx)
+                            .and_then(|session| session.read(cx).mode().as_running().cloned())
+                    }) {
+                        active_item.update(cx, |item, cx| item.pause_thread(cx))
+                    }
+                })
+                .register_action(|workspace, _: &Restart, _, cx| {
+                    let debug_panel = workspace.panel::<DebugPanel>(cx).unwrap();
+
+                    if let Some(active_item) = debug_panel.read_with(cx, |panel, cx| {
+                        panel
+                            .active_session(cx)
+                            .and_then(|session| session.read(cx).mode().as_running().cloned())
+                    }) {
+                        active_item.update(cx, |item, cx| item.restart_session(cx))
+                    }
+                })
+                .register_action(|workspace, _: &StepInto, _, cx| {
+                    let debug_panel = workspace.panel::<DebugPanel>(cx).unwrap();
+
+                    if let Some(active_item) = debug_panel.read_with(cx, |panel, cx| {
+                        panel
+                            .active_session(cx)
+                            .and_then(|session| session.read(cx).mode().as_running().cloned())
+                    }) {
+                        active_item.update(cx, |item, cx| item.step_in(cx))
+                    }
+                })
+                .register_action(|workspace, _: &StepOver, _, cx| {
+                    let debug_panel = workspace.panel::<DebugPanel>(cx).unwrap();
+
+                    if let Some(active_item) = debug_panel.read_with(cx, |panel, cx| {
+                        panel
+                            .active_session(cx)
+                            .and_then(|session| session.read(cx).mode().as_running().cloned())
+                    }) {
+                        active_item.update(cx, |item, cx| item.step_over(cx))
+                    }
+                })
+                .register_action(|workspace, _: &StepBack, _, cx| {
+                    let debug_panel = workspace.panel::<DebugPanel>(cx).unwrap();
+
+                    if let Some(active_item) = debug_panel.read_with(cx, |panel, cx| {
+                        panel
+                            .active_session(cx)
+                            .and_then(|session| session.read(cx).mode().as_running().cloned())
+                    }) {
+                        active_item.update(cx, |item, cx| item.step_back(cx))
+                    }
+                })
+                .register_action(|workspace, _: &Stop, _, cx| {
+                    let debug_panel = workspace.panel::<DebugPanel>(cx).unwrap();
+
+                    if let Some(active_item) = debug_panel.read_with(cx, |panel, cx| {
+                        panel
+                            .active_session(cx)
+                            .and_then(|session| session.read(cx).mode().as_running().cloned())
+                    }) {
+                        active_item.update(cx, |item, cx| item.stop_thread(cx))
+                    }
+                })
+                .register_action(|workspace, _: &ToggleIgnoreBreakpoints, _, cx| {
+                    let debug_panel = workspace.panel::<DebugPanel>(cx).unwrap();
+
+                    if let Some(active_item) = debug_panel.read_with(cx, |panel, cx| {
+                        panel
+                            .active_session(cx)
+                            .and_then(|session| session.read(cx).mode().as_running().cloned())
+                    }) {
+                        active_item.update(cx, |item, cx| item.toggle_ignore_breakpoints(cx))
+                    }
+                })
+                .register_action(
+                    |workspace: &mut Workspace, _: &ShutdownDebugAdapters, _window, cx| {
+                        workspace.project().update(cx, |project, cx| {
+                            project.dap_store().update(cx, |store, cx| {
+                                store.shutdown_sessions(cx).detach();
+                            })
+                        })
+                    },
+                );
+        })
+    })
+    .detach();
+}