Add GPT-OSS architecture adapter tests

[RecreationalMath]

Description

Adds a unit test suite for GPTOSSArchitectureAdapter under tests/unit/model_bridge/supported_architectures/, following the existing adapter-test pattern (modeled on the merged mixtral and olmoe suites). It needs no model downloads or real checkpoints: it uses tiny programmatic TransformerBridgeConfig objects, plus small synthetic tensors and a fake attention module for the behavioral tests, so it runs on CPU in seconds.

The suite (44 tests) covers:

• Adapter config defaults (RMSNorm, rotary, gated MoE MLP, eps_attr = "variance_epsilon").
• Weight conversions: the four QKVO weights (GPT-OSS has no projection biases), with GQA-aware head counts and the no-n_key_value_heads fallback.
• Numerical round-trips: the rearrange conversions are actually run on synthetic HF-shaped weight tensors, asserting the split-head output shapes and lossless reversion.
• Component-mapping structure, bridge types, and HF module paths, including the MoE bridge with no exposed submodules (the entire MoE block is wrapped opaquely).
• Factory registration and dispatch via select_architecture_adapter.
• GQA forward hook shapes: a fake attention module wired into the bridge confirms Q surfaces n_heads while K/V surface n_key_value_heads.
• setup_hook_compatibility rotary-embedding wiring on a bridge model: a no-op when bridge_model is None or lacks rotary_emb, sets rotary on each block's attention bridge when present, skips blocks without attention, and setup_no_processing_hooks (the backward-compat alias) produces the same wiring.
• Architecture guards against drift.

Contributes to #1302 (GPT-OSS checkbox).

Type of change

• New feature (non-breaking change which adds functionality)

Checklist:

• I have commented my code, particularly in hard-to-understand areas
• My changes generate no new warnings
• I have added tests that prove my fix is effective or that my feature works
• New and existing unit tests pass locally with my changes
• I have not rewritten tests relating to key interfaces which would affect backward compatibility

[jlarson4]

Excellent test suite, thank you @RecreationalMath