[mlir] Split out Python bindings for dialects into separate libs

Historically, the bindings for the Linalg dialect were included into the
"core" bindings library because they depended on the C++ implementation
of the "core" bindings. The other dialects followed the pattern. Now
that this dependency is gone, split out each dialect into a separate
Python extension library.

Depends On D116649, D116605

Reviewed By: stellaraccident

Differential Revision: https://reviews.llvm.org/D116662

mlir/lib/Bindings/Python/MainModule.cpp

@@ -10,7 +10,6 @@
 
 #include "PybindUtils.h"
 
-#include "Dialects.h"
 #include "Globals.h"
 #include "IRModule.h"
 #include "Pass.h"
@@ -100,13 +99,4 @@ PYBIND11_MODULE(_mlir, m) {
   auto passModule =
       m.def_submodule("passmanager", "MLIR Pass Management Bindings");
   populatePassManagerSubmodule(passModule);
-
-  // Define and populate dialect submodules.
-  auto dialectsModule = m.def_submodule("dialects");
-  auto linalgModule = dialectsModule.def_submodule("linalg");
-  populateDialectLinalgSubmodule(linalgModule);
-  populateDialectSparseTensorSubmodule(
-      dialectsModule.def_submodule("sparse_tensor"), irModule);
-  populateDialectQuantSubmodule(dialectsModule.def_submodule("quant"),
-                                irModule);
 }