debugger: Fix issues with launch.json handling (#32563)

After this PR we can run all the in-tree launch.json examples from [this
repo](https://github.com/microsoft/vscode-recipes).

Things done:

- Fill in default cwd at a lower level for all adapters
- Update launch.json parsing for DebugScenario changes
- Imitate how VS Code normalizes the `type` field for JS debug tasks
- Make version field optional
- Extend the variable replacer a bit

Release Notes:

- Debugger Beta: fixed issues preventing loading and running of debug
tasks from VS Code's launch.json.

---------

Co-authored-by: Anthony Eid <hello@anthonyeid.me>
Co-authored-by: Anthony <anthony@zed.dev>
Co-authored-by: Conrad Irwin <conrad.irwin@gmail.com>

crates/dap_adapters/src/gdb.rs

@@ -177,10 +177,12 @@ impl DebugAdapter for GdbDebugAdapter {
 
         let gdb_path = user_setting_path.unwrap_or(gdb_path?);
 
-        let request_args = StartDebuggingRequestArguments {
-            request: self.request_kind(&config.config)?,
-            configuration: config.config.clone(),
-        };
+        let mut configuration = config.config.clone();
+        if let Some(configuration) = configuration.as_object_mut() {
+            configuration
+                .entry("cwd")
+                .or_insert_with(|| delegate.worktree_root_path().to_string_lossy().into());
+        }
 
         Ok(DebugAdapterBinary {
             command: Some(gdb_path),
@@ -188,7 +190,10 @@ impl DebugAdapter for GdbDebugAdapter {
             envs: HashMap::default(),
             cwd: Some(delegate.worktree_root_path().to_path_buf()),
             connection: None,
-            request_args,
+            request_args: StartDebuggingRequestArguments {
+                request: self.request_kind(&config.config)?,
+                configuration,
+            },
         })
     }
 }