Enable loc info when printing .ttir .ttgir (triton-lang#2736)

Summary: in triton.cc, enable_debug on PM will make sure debugging info
is dumped when MLIR_ENABLE_DUMP is on. But for printing .ttir .ttgir, we
are using the default OpPrintingFlags for Operation::print: const
OpPrintingFlags &flags = std::nullopt

With this patch, we pass in OpPrintingFlags with debug info enabled.

Since the generation of debug info is controlled via env var:
TRITON_DISABLE_LINE_INFO, it should be okay to print loc info as long as
it exists.

Co-authored-by: Manman Ren <mren@meta.com>

python/src/triton.cc

@@ -461,7 +461,9 @@ void init_triton_ir(py::module &&m) {
            [](mlir::OpState &self) -> std::string {
              std::string str;
              llvm::raw_string_ostream os(str);
-             self->print(os);
+             auto printingFlags = mlir::OpPrintingFlags();
+             printingFlags.enableDebugInfo();
+             self->print(os, printingFlags);
              return str;
            })
       .def("append_operand",
@@ -498,7 +500,9 @@ void init_triton_ir(py::module &&m) {
            [](mlir::ModuleOp &self) -> std::string {
              std::string str;
              llvm::raw_string_ostream os(str);
-             self.print(os);
+             auto printingFlags = mlir::OpPrintingFlags();
+             printingFlags.enableDebugInfo();
+             self.print(os, printingFlags);
              return str;
            })
       .def("bytecode",