[mlir][nfc] Allow ops to have operands/attributes named `context`.

[csigg]

Summary

This is probably a bad idea, but it's only become a problem with properties and is easy to fix.

[csigg]

Rebase.

mlir/include/mlir/IR/OperationSupport.h

struct Model : public Impl {
 
     using Properties = std::remove_reference_t<
         decltype(std::declval<ConcreteOp>().getProperties())>;
 
     std::optional<Attribute> getInherentAttr(Operation *op,
                                              StringRef name) final {
       if constexpr (hasProperties) {
         auto concreteOp = cast<ConcreteOp>(op);
-        return ConcreteOp::getInherentAttr(concreteOp.getContext(),
+        return ConcreteOp::getInherentAttr(concreteOp->getContext(),
                                            concreteOp.getProperties(), name);
       }
       // If the op does not have support for properties, we dispatch back to the
       // dictionnary of discardable attributes for now.
       return cast<ConcreteOp>(op)->getDiscardableAttr(name);
     }
     void setInherentAttr(Operation *op, StringAttr name,
                          Attribute value) final {
       if constexpr (hasProperties) {
         auto concreteOp = cast<ConcreteOp>(op);
         return ConcreteOp::setInherentAttr(concreteOp.getProperties(), name,
                                            value);
       }
       // If the op does not have support for properties, we dispatch back to the
       // dictionnary of discardable attributes for now.
       return cast<ConcreteOp>(op)->setDiscardableAttr(name, value);
     }
     void populateInherentAttrs(Operation *op, NamedAttrList &attrs) final {
       if constexpr (hasProperties) {
         auto concreteOp = cast<ConcreteOp>(op);
-        ConcreteOp::populateInherentAttrs(concreteOp.getContext(),
+        ConcreteOp::populateInherentAttrs(concreteOp->getContext(),
                                           concreteOp.getProperties(), attrs);
       }
     }
     LogicalResult
     verifyInherentAttrs(OperationName opName, NamedAttrList &attributes,
                         function_ref<InFlightDiagnostic()> getDiag) final {
       if constexpr (hasProperties)
         return ConcreteOp::verifyInherentAttrs(opName, attributes, getDiag);