feat(rdbg): support attach requests for rdbg debugger (#124)

Implement support for attach debugging requests in the Ruby
debugger. Previously, attach requests were unsupported and would
return an error. Now, we support the default `rdbg` configuration:

```json
{
  "label": "Attach to Rails server",
  "adapter": "rdbg",
  "request": "attach",
  "cwd": "$ZED_WORKTREE_ROOT",
  "env": {
    "RUBY_DEBUG_PORT": "52203"
  }
}
```

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---
This is **part 2 of 2 in a stack** made with GitButler:
- <kbd>&nbsp;2&nbsp;</kbd> #124 👈 
- <kbd>&nbsp;1&nbsp;</kbd> #123 
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Author: vitallium

src/ruby.rs

@@ -192,18 +192,25 @@ impl zed::Extension for RubyExtension {
             arguments.push(format!("--port={}", connection.port));
         }
 
-        if let Some(script) = &ruby_config.script {
-            arguments.push(script.clone());
-        } else if let Some(command) = &ruby_config.command {
-            arguments.push("--command".to_string());
-            arguments.push(command.clone());
-        } else if let Some(command_or_script) = &ruby_config.script_or_command {
-            if worktree.which(command_or_script).is_some() {
-                arguments.push("--command".to_string());
+        match self.dap_request_kind(adapter_name, configuration.clone())? {
+            StartDebuggingRequestArgumentsRequest::Launch => {
+                if let Some(script) = &ruby_config.script {
+                    arguments.push(script.clone());
+                } else if let Some(command) = &ruby_config.command {
+                    arguments.push("--command".to_string());
+                    arguments.push(command.clone());
+                } else if let Some(command_or_script) = &ruby_config.script_or_command {
+                    if worktree.which(command_or_script).is_some() {
+                        arguments.push("--command".to_string());
+                    }
+                    arguments.push(command_or_script.clone());
+                } else {
+                    return Err("Ruby debug config must have 'script' or 'command' args".into());
+                }
+            }
+            StartDebuggingRequestArgumentsRequest::Attach => {
+                // Do nothing
             }
-            arguments.push(command_or_script.clone());
-        } else {
-            return Err("Ruby debug config must have 'script' or 'command' args".into());
         }
 
         if let Some(configuration) = configuration.as_object_mut() {
@@ -276,7 +283,28 @@ impl zed::Extension for RubyExtension {
                     build: None,
                 })
             }
-            DebugRequest::Attach(_) => Err("Attach requests are unsupported".into()),
+            DebugRequest::Attach(_) => {
+                let config = RubyDebugConfig {
+                    script_or_command: None,
+                    script: None,
+                    command: None,
+                    args: vec![],
+                    env: Default::default(),
+                    cwd: None,
+                };
+
+                let config = serde_json::to_value(config)
+                    .map_err(|e| e.to_string())?
+                    .to_string();
+
+                Ok(DebugScenario {
+                    adapter: zed_scenario.adapter,
+                    label: zed_scenario.label,
+                    config,
+                    tcp_connection: None,
+                    build: None,
+                })
+            }
         }
     }
 }