chore: Add type hints to import_utils.py module

[wirthual]

What does this PR do?

Add type hints to import_utils.py

Based on these docs, this change should avoid errors like:

infinity_emb/inference/loading_strategy.py:10: error: Skipping analyzing "transformers.utils.import_utils": module is installed, but missing library stubs or py.typed marker  [import-untyped]

Before submitting

• Did you read the contributor guideline,
  Pull Request section?

Who can review?

@stevhliu

[wirthual]

Failed image download reason for test failure.

See #40000

[stevhliu]

cc @Rocketknight1