[mlir][async] Add AutomaticAllocationScope to async::ExecuteOp

[mehdi_amini]

Please provide motivation in your commit description!

This kind of changes shouldn't just have a descriptive title that does not provide much information in itself...

[bondhugula]

In D118761#3292527, @mehdi_amini wrote:

Please provide motivation in your commit description!

This kind of changes shouldn't just have a descriptive title that does not provide much information in itself...

+1. Commit summaries should never be left blank, particularly for a commit like this. I would recommend reverting and re-applying with a proper summary.

mlir/include/mlir/Dialect/Async/IR/AsyncOps.td

 // Base class for the operation in this dialect
 class Async_Op<string mnemonic, list<Trait> traits = []> :
     Op<AsyncDialect, mnemonic, traits>;
 
 def Async_ExecuteOp :
   Async_Op<"execute", [SingleBlockImplicitTerminator<"YieldOp">,
                        DeclareOpInterfaceMethods<RegionBranchOpInterface,
                                                  ["getSuccessorEntryOperands"]>,
-                       AttrSizedOperandSegments]> {
+                       AttrSizedOperandSegments,
+                       AutomaticAllocationScope]> {
   let summary = "Asynchronous execute operation";
   let description = [{
     The `body` region attached to the `async.execute` operation semantically
     can be executed concurrently with the successor operation. In the followup
     example "compute0" can be executed concurrently with "compute1".
 
     The actual concurrency semantics depends on the dialect lowering to the
     executable format. Fully sequential execution ("compute0" completes before