Declare experimental Amazon Bedrock setup APIs (#39277)

## What changed

- Add experimental `account/bedrock/discover` and `account/bedrock/setup`
  requests to the app-server protocol.
- Define discovery results for AWS profiles and environment credentials, plus
  setup inputs for profiles, environment credentials, and access keys.
- Export the new types in the experimental protocol schema. The app server
  currently returns `method not found` for both requests because setup is not
  yet implemented.

GitOrigin-RevId: 656b4bc11231a417e97041068cecc5dc692786e3

codex-rs/app-server-protocol/src/export.rs

@@ -44,6 +44,9 @@ pub(crate) const GENERATED_TS_HEADER: &str = "// GENERATED CODE! DO NOT MODIFY B
 const IGNORED_DEFINITIONS: &[&str] = &["Option<()>"];
 const JSON_V1_ALLOWLIST: &[&str] = &["InitializeParams", "InitializeResponse"];
 const EXPERIMENTAL_CLIENT_METHOD_DEPENDENCY_TYPES: &[&str] = &[
+    "AwsCredentialType",
+    "BedrockAwsProfile",
+    "BedrockEnvironmentCredential",
     "EnvironmentShellInfo",
     "EnvironmentStatusKind",
     "RemoteControlClient",