Introduces a test pass that rewrites PadTensorOps with static shapes as a sequence of:
```
linalg.init_tensor // to create output
linalg.fill // to initialize with padding value
linalg.generic // to copy the original contents to the padded tensor
```
The pass can be triggered with:
- `--test-linalg-transform-patterns="test-transform-pad-tensor"`
Differential Revision: https://reviews.llvm.org/D102804
0804a88e48