Base: simplify UnitsSchemas management

Fixes: Maintaining schemas is difficult and error-prone

- Facilitate easy schemas add, remove, change, etc.
- Remove 14 files containing approx 2,190 lines of if/else code and data
- Place data in one file (UnitsSchemasData.h) using a normalized structure (including special functions)
- Isolate and simplify data operations (code)
- Remove schemas enum to keep data independent of code
- Separate responsibilities: Specifications, data, schemas, schema
- Add schema data 'isDefault'
- Add schema data name
- Prefer algorithms to raw loops
- Add schemas unit tests
- Tweak quantity unit tests

src/App/Document.cpp

@@ -876,13 +876,8 @@ Document::Document(const char* documentName)
                       "Additional tag to save the name of the company");
     ADD_PROPERTY_TYPE(UnitSystem, (""), 0, Prop_None, "Unit system to use in this project");
     // Set up the possible enum values for the unit system
-    int num = static_cast<int>(Base::UnitSystem::NumUnitSystemTypes);
-    std::vector<std::string> enumValsAsVector;
-    for (int i = 0; i < num; i++) {
-        QString item = Base::UnitsApi::getDescription(static_cast<Base::UnitSystem>(i));
-        enumValsAsVector.emplace_back(item.toStdString());
-    }
-    UnitSystem.setEnums(enumValsAsVector);
+
+    UnitSystem.setEnums(Base::UnitsApi::getDescriptions());
     // Get the preferences/General unit system as the default for a new document
     ParameterGrp::handle hGrpu =
         App::GetApplication().GetParameterGroupByPath("User parameter:BaseApp/Preferences/Units");