Add timm models export

[mht-sharma]

What does this PR do?

Add export for large number of Timm models

• Introduced DefaultTimmConfig to facilitate Timm model exports.
  • The Timm configuration entails the architecture, synonymous with model_type in transformers. However, the architecture comprises multiple variations for input_size, hidden_layers, etc.
  • This results in numerous architecture types for a single model, making it impractical to incorporate all in the TaskManager.
  • The addition of DefaultTimmConfig streamlines support for all Timm models. Specific cases can still be added similarly to other exports.
  • This design works best for this library, and changes do not affect other exports
• This repository now accommodates over 1000 models available on the https://huggingface.co/timm page.

Before submitting

• This PR fixes a typo or improves the docs (you can dismiss the other checks if that's the case).
• Did you make sure to update the documentation with your changes?
• Did you write any new necessary tests?

[mht-sharma]

Question: For TImm tests, should I add all the supported models based on architecture for testing, which would be a large number.
Best is manually selecting one for each model mentioned here: https://huggingface.co/docs/timm/models/. WDYT