Add Phi-4 model

[yrahul3910]

Is your feature request related to a problem? Please describe.

I want to contribute the Phi-4 multimodal model. I plan to base the implementation off the technical report, so I will likely use the Phi-3 code as a starting point (since it's most similar to phi-3-medium).

Describe the solution you'd like

As described in the model contributing guide, I will create at least 3 PRs in order.

Describe alternatives you've considered

N/A

Additional context

N/A