Add qwen3 and llava_next adapter tests

[sunny1401]

Description

Adds unit test suites for Qwen3ArchitectureAdapter and LlavaNextArchitectureAdapter under tests/unit/model_bridge/supported_architectures/.

Contributes to #1302 (Qwen3 + LlavaNext checkboxes).

Type of change

[ x] New feature (non-breaking change which adds functionality)

Please delete options that are not relevant.

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