feat: Magnitude / Unit operator added

src/core/include/mp-units/unit.h

@@ -430,6 +430,15 @@ template<Unit Lhs, Unit Rhs>
     return detail::expr_multiply<derived_unit, struct one, detail::type_list_of_unit_less>(lhs, rhs);
 }
 
+/**
+ * Returns the result of multiplication with an inverse unit.
+ */
+template<Magnitude M, Unit U>
+[[nodiscard]] MP_UNITS_CONSTEVAL Unit auto operator/(M mag, const U u)
+{
+  return mag * (1 / u);
+}
+
 /**
  * `scaled_unit` specializations have priority in this operation. This means that the library framework
  * prevents passing it as an element to the `derived_unit`. In such case only the reference unit is passed

src/systems/si/include/mp-units/systems/si/constants.h

@@ -41,7 +41,7 @@ inline constexpr struct elementary_charge :
 inline constexpr struct boltzmann_constant :
   named_unit<"k", mag<ratio{1'380'649, 1'000'000}> * mag_power<10, -23> * joule / kelvin> {} boltzmann_constant;
 inline constexpr struct avogadro_constant :
-  named_unit<"N_A", mag<ratio{602'214'076, 100'000'000}> * mag_power<10, 23> * (1 / mole)> {} avogadro_constant;
+  named_unit<"N_A", mag<ratio{602'214'076, 100'000'000}> * mag_power<10, 23> / mole> {} avogadro_constant;
 inline constexpr struct luminous_efficacy :
   named_unit<"K_cd", mag<683> * lumen / watt> {} luminous_efficacy;
 // clang-format on