Add prefix milli to torr unit (#1588)

Hello, it's me again !

This time, I'm adding prefix milli for Torr unit, although it's not part
of the SI, the millitorr is widely used in scientific and industrial
vacuum applications.

Let me know if you have any feedback !

Author: n-tiz

Common/UnitDefinitions/Pressure.json

@@ -198,6 +198,7 @@
       "XmlDocRemarks": "https://en.wikipedia.org/wiki/Torr",
       "FromUnitToBaseFunc": "{x} * 101325 / 760",
       "FromBaseToUnitFunc": "{x} * 760 / 101325",
+      "Prefixes": [ "Milli"],
       "Localization": [
         {
           "Culture": "en-US",

Common/UnitEnumValues.g.json

@@ -1183,7 +1183,8 @@
     "TonneForcePerSquareMillimeter": 46,
     "Torr": 47,
     "MeterOfWaterColumn": 57,
-    "CentimeterOfWaterColumn": 48
+    "CentimeterOfWaterColumn": 48,
+    "Millitorr": 52
   },
   "PressureChangeRate": {
     "AtmospherePerSecond": 1,

UnitsNet.NanoFramework/GeneratedCode/Quantities/Pressure.g.cs

@@ -67,6 +67,8 @@ public class PressureTests : PressureTestsBase
 
         protected override double TorrsInOnePascal => 7.5006 * 1E-3;
 
+        protected override double MillitorrsInOnePascal => 7.5006;
+
         protected override double CentibarsInOnePascal => 1e-3;
 
         protected override double DecapascalsInOnePascal => 1e-1;