Add support for Moonshine ONNX export (& models with non-legacy cache & Tensor.repeat_interleave)

[xenova]

What does this PR do?

This PR does the following:

• Adds ONNX export support for Moonshine
• Adds support for models which previously failed due to usage of torch.Tensor.repeat_interleave, which are unable to export due to a bug in pytorch: torch.onnx.export (dynamo=False) fails with uninformative error when exporting apply_rotary_pos_emb/repeat_interleave pytorch/pytorch#145100. Note that this bug most likely won't be fixed as the pytorch team transitions to the new dynamo-based exporter.
• Adds support for models which do not utilize the legacy caching system (instead, using the new Cache class)

TODOs:

• In certain cases, repeat_interleave works correctly (perhaps with dim != -1?). Ideally, we'd fallback to the working ONNX version whenever possible.
• Add unit tests
• Update docs

Fixes # (issue)

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?

Who can review?