Dynamic Conv1d + W2L (#2976)

Summary:
Pull Request resolved: https://github.com/pytorch/executorch/pull/2976

Conv1d uses static reshape operator, in order to convert 3d tensor to 4d tensor so xnnpack can operate using conv2d.

For dynamism, reshape only accepts a single dynamic dimension, which is denoted as dynamic with a dim of 0.

Reviewed By: digantdesai, kirklandsign

Differential Revision: D55815092

fbshipit-source-id: a3c96bc5c86c130291c1d54f8174a6ff5d25a6b8