Add custom builder to reduce op allowing type inference

[sdasgup3]

The PR implements the a custom reduce op builder similar to what we have for mhlo code.

Background

#1869 allows the block arguments of reduce op to have different element types than that of the input arguments of reduce op and the output element type of the reduce op has to equal to those block arguments. As a consequence the output type of reduce op can no longer be inferred from the operand types. The auto-generated builders creates a reduce op with empty block and, as a result, does not allow inferring the type.

The proposed solution is to create a custom builder which takes the element-type of the block arguments as arguments allowing result type inference.

[mlevesquedion]

LGTM. Consider adding some kind of test for this builder.

[sjain-stanford]

@sdasgup3 Gently checking-in on this, and appreciate your help here. Unfortunately cherry-picking from your fork doesn't play well with the git submodule setup in torch-mlir which expects a commit on main, so I can't proceed with the fix without this landing.

 Error: fatal: Fetched in submodule path 'externals/stablehlo', but it did not contain f2b6877713027370f26569929fb5d841a79d3589. Direct fetching of that commit failed.