Add Btu/ft² in irradiation (#1364)

Added a new unit Btu/ft² in irradiation. This is commonly used in
building industry.

---------

Co-authored-by: Andreas Gullberg Larsen <[email protected]>

Author: MingboPeng

Common/UnitDefinitions/Irradiation.json

@@ -58,6 +58,19 @@
           "Abbreviations": [ "Wh/m²" ]
         }
       ]
+    },
+    {
+      "SingularName": "BtuPerSquareFoot",
+      "PluralName": "BtusPerSquareFoot",
+      "FromUnitToBaseFunc": "{x} * (52752792631d / 4645152d)",
+      "FromBaseToUnitFunc": "{x} / (52752792631d / 4645152d)",
+      "Prefixes": [ "Kilo" ],
+      "Localization": [
+        {
+          "Culture": "en-US",
+          "Abbreviations": [ "Btu/ft²" ]
+        }
+      ]
     }
   ]
 }

Common/UnitEnumValues.g.json

@@ -631,7 +631,9 @@
     "KilojoulePerSquareMeter": 4,
     "KilowattHourPerSquareMeter": 5,
     "MillijoulePerSquareCentimeter": 6,
-    "WattHourPerSquareMeter": 7
+    "WattHourPerSquareMeter": 7,
+    "BtuPerSquareFoot": 15,
+    "KilobtuPerSquareFoot": 9
   },
   "Jerk": {
     "CentimeterPerSecondCubed": 1,

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

@@ -41,5 +41,9 @@ public class IrradiationTests : IrradiationTestsBase
         protected override double WattHoursPerSquareMeterInOneJoulePerSquareMeter => 2.777777777777778e-4;
 
         protected override double KilowattHoursPerSquareMeterInOneJoulePerSquareMeter => 2.777777777777778e-7;
+
+        protected override double BtuPerSquareFootInOneJoulePerSquareMeter => 8.805509170334624e-5;
+
+        protected override double KilobtuPerSquareFootInOneJoulePerSquareMeter => 8.805509170334624e-8;
     }
 }