[DT][NFCI] Switch SetEncoding pass to walk-based pass. (iree-org#21662)

- Move the requirements to `isSupportedContractionOp`.
- Convert `SetContractionOpEncoding::matchAndRewrite` to
`setDataTilingEncodings` method.
- Collect all the candidates, iterate and set encoding for each
candidate.
- Refactor `postPatterns` for all the strategies.

It is a step towards iree-org#21246

---------

Signed-off-by: hanhanW <[email protected]>
Signed-off-by: keshavvinayak01 <[email protected]>

Author: hanhanW

compiler/src/iree/compiler/DispatchCreation/Passes.td

@@ -329,6 +329,10 @@ def PropagateEncodingsPass :
 def SetEncodingPass : InterfacePass<"iree-dispatch-creation-set-encoding",
                                     "mlir::FunctionOpInterface"> {
   let summary = "Introduces tensor encoding for flow dispatch regions.";
+  let description = [{
+    Sets the encoding for compute operations to allow execution of the
+    operations in tiled/padded layouts.
+  }];
   let dependentDialects = [
     "mlir::linalg::LinalgDialect",
     "IREE::Flow::FlowDialect",