[fir][NFC] Move MLIR includes to FIRDialect.td

[clementval]

Summary

The fir_Dialect definition was coming silently through FIRTypes.td.
Make the include of flang/Optimizer/Dialect/FIRDialect.td explicit in
FIROps.td and move MLIR includes to FIRDialect.td.

This patch is part of the upstreaming effort from fir-dev branch.

Co-authored-by: Eric Schweitz <[e-mail]>

[AlexisPerry]

LGTM

flang/include/flang/Optimizer/Dialect/FIRDialect.td

 //===-- FIRDialect.td - FIR dialect definition -------------*- tablegen -*-===//
 //
 // Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
 // See https://llvm.org/LICENSE.txt for license information.
 // SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
 //
 //===----------------------------------------------------------------------===//
 ///
 /// \file
 /// Definition of the FIR dialect
 ///
 //===----------------------------------------------------------------------===//
 
 #ifndef FORTRAN_DIALECT_FIR_DIALECT
 #define FORTRAN_DIALECT_FIR_DIALECT
 
+include "mlir/IR/SymbolInterfaces.td"
+include "mlir/Interfaces/CallInterfaces.td"
+include "mlir/Interfaces/ControlFlowInterfaces.td"
+include "mlir/Interfaces/LoopLikeInterface.td"
+include "mlir/Interfaces/SideEffectInterfaces.td"
+
 def fir_Dialect : Dialect {
   let name = "fir";
   let cppNamespace = "::fir";
 }
 
 #endif // FORTRAN_DIALECT_FIR_DIALECT

flang/include/flang/Optimizer/Dialect/FIROps.td

 //===-- FIROps.td - FIR operation definitions --------------*- tablegen -*-===//
 //
 // Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
 // See https://llvm.org/LICENSE.txt for license information.
 // SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
 //
 //===----------------------------------------------------------------------===//
 ///
 /// \file
 /// Definition of the FIR dialect operations
 ///
 //===----------------------------------------------------------------------===//
 
 #ifndef FORTRAN_DIALECT_FIR_OPS
 #define FORTRAN_DIALECT_FIR_OPS
 
-include "mlir/IR/SymbolInterfaces.td"
-include "mlir/Interfaces/CallInterfaces.td"
-include "mlir/Interfaces/ControlFlowInterfaces.td"
-include "mlir/Interfaces/LoopLikeInterface.td"
-include "mlir/Interfaces/SideEffectInterfaces.td"
+include "flang/Optimizer/Dialect/FIRDialect.td"
 include "flang/Optimizer/Dialect/FIRTypes.td"
 
 // Base class for FIR operations.
 // All operations automatically get a prefix of "fir.".
 class fir_Op<string mnemonic, list<OpTrait> traits>
   : Op<fir_Dialect, mnemonic, traits>;
 
 // Base class for FIR operations that take a single argument