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/protocol/v2/mod.rs

@@ -3,6 +3,7 @@ mod shared;
 mod account;
 mod apps;
 mod attestation;
+mod bedrock;
 mod collaboration_mode;
 mod command_exec;
 mod config;
@@ -34,6 +35,7 @@ mod windows_sandbox;
 pub use account::*;
 pub use apps::*;
 pub use attestation::*;
+pub use bedrock::*;
 pub use collaboration_mode::*;
 pub use command_exec::*;
 pub use config::*;