[MLIR][LaunchFuncToLLVM] Remove typed pointer support (#70840)

This commit removes the typed pointer support from the LaunchFunc's
lowering to LLVM dialect. Typed pointers have been deprecated for a
while now and it's planned to soon remove them from the LLVM dialect.

Related PSA:
https://discourse.llvm.org/t/psa-removal-of-typed-pointers-from-the-llvm-dialect/74502