vysion: lazy-import Vysion deps to work around Python 3.13/3.14 import failures

[adulau]

Motivation

• Top-level vysion imports cause import-time failures on Python 3.13/3.14 (likely due to a transitive dependency such as softenum), breaking module registration; the change defers those imports so the package can load on all supported runtimes and fail gracefully at runtime when used.

Description

• Remove top-level vysion imports and add a _load_vysion_dependencies() helper that imports vysion.client and vysion.dto.util.MISPProcessor lazily and raises a clear RuntimeError on failure.
• Call _load_vysion_dependencies() inside handler() so the module only requires vysion at runtime when actually invoked.
• Add a dedicated RuntimeError handling path with an actionable message, and broaden the generic exception handling to avoid relying on provider-specific exception classes during import-time failures.

Testing

• Ran python -m py_compile misp_modules/modules/expansion/vysion.py, which succeeded.
• Verified the change is limited to misp_modules/modules/expansion/vysion.py and that the module now reports a clear runtime error if vysion (or its transitive deps) cannot be imported.

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Codex Task