update set_tensor_data to use MethodMeta and set_input (#524)

Summary:
Pull Request resolved: https://github.com/pytorch/executorch/pull/524

Switch the util used in all of our examples to use "set_input" instead of get_input, set_data.

Theres still more work to be done on this util like make it follow our style guide, put it in a more specific file, use RAII but thatll be after MVP.

Reviewed By: dbort

Differential Revision: D49747239

fbshipit-source-id: 01d42f11080cdf4fb6b185235e9d6dfad36a6e49