Make change of HbA1c unit persistent

(cherry picked from commit 6415c3ec58a2b4d1d21ef9d4fc921b60484ba0bf)

FreeAPS/Sources/Models/FreeAPSSettings.swift

@@ -204,6 +204,10 @@ extension FreeAPSSettings: Decodable {
         if let rulerMarks = try? container.decode(Bool.self, forKey: .rulerMarks) {
             settings.rulerMarks = rulerMarks
         }
+        
+        if let overrideHbA1cUnit = try? container.decode(Bool.self, forKey: .overrideHbA1cUnit) {
+            settings.overrideHbA1cUnit = overrideHbA1cUnit
+        }
 
         self = settings
     }

FreeAPS/Sources/Modules/Home/HomeStateModel.swift

@@ -53,7 +53,7 @@ extension Home {
         @Published var maxValue: Decimal = 1.2
         @Published var lowGlucose: Decimal = 4 / 0.0555
         @Published var highGlucose: Decimal = 10 / 0.0555
-        @Published var overrideUnit = false
+        @Published var overrideUnit: Bool = false
         @Published var screenHours: Int = 6
         @Published var displayXgridLines: Bool = false
         @Published var displayYgridLines: Bool = false