ENH: make op names unambiguous

* lessEqOp    -> lessEqualOp
  * greaterEqOp -> greaterEqualOp

  to avoid ambiguitity with other forms such as 'plusEqOp' where the
  'Eq' implies an assigment. The name change also aligns better with
  C++ <functional> names such as std::less_equal, std::greater_equal

ENH: simple labelRange predicates gt0/ge0/lt0/le0

- mirrors scalarRange tests.
  Lower overhead than using labelMinMax::ge(0) etc since it does not
  create an intermediate (is stateless) and can be used as a constexpr

src/functionObjects/field/blendingFactor/blendingFactor.C

@@ -116,7 +116,7 @@ bool Foam::functionObjects::blendingFactor::read(const dictionary& dict)
             (
                 "tolerance",
                 0.001,
-                [&](const scalar tol){ return (tol > 0) && (tol < 1); }
+                [](scalar tol){ return (tol > 0 && tol < 1); }
             );
 
         return true;

src/functionObjects/lagrangian/common/parcelSelectionDetail.H

@@ -98,9 +98,9 @@ Description
     The expressions are a (op scalar) pair that form a unary scalar
     predicate. The \a op is one of the following:
     - lt, less
-    - le, lessEq
+    - le, lessEqual, lessEq
     - gt, greater
-    - ge, greaterEq
+    - ge, greaterEqual, greaterEq
     - eq, equal
     - neq, notEqual