[mlir][Linalg] Add ConvolutionOpInterface.

Add an interface that allows grouping together all covolution and
pooling ops within Linalg named ops. The interface currently
- the indexing map used for input/image access is valid
- the filter and output are accessed using projected permutations
- that all loops are charecterizable as one iterating over
  - batch dimension,
  - output image dimensions,
  - filter convolved dimensions,
  - output channel dimensions,
  - input channel dimensions,
  - depth multiplier (for depthwise convolutions)

Differential Revision: https://reviews.llvm.org/D109793