refactor: Split converters.dart and index.dart into individual files

Splits the `mapper/lib/src/model/converters.dart` and `mapper/lib/src/model/index.dart` files into individual files. This improves maintainability and readability of the code.

- Created new directories `mapper/lib/src/model/converters` and `mapper/lib/src/model/index`.
- Moved each class and definition to its own file within the new directories.
- Replaced the original `converters.dart` and `index.dart` with barrel files that export all the new files, ensuring no breaking changes for existing importers.
- Added a newline to the end of all new files.

Author: google-labs-jules[bot]

mapper/lib/src/model/converters/base_converter.dart

@@ -53,4 +53,4 @@ class BaseCustomConverter {
         ? jsonProperty.converterParams![name]
         : null;
   }
-}
+}

mapper/lib/src/model/converters/bigint_converter.dart

@@ -16,4 +16,4 @@ class BigIntConverter implements ICustomConverter {
   dynamic toJSON(Object? object, SerializationContext context) {
     return object is BigInt ? object.toString() : object;
   }
-}
+}

mapper/lib/src/model/converters/date_converter.dart

@@ -36,4 +36,4 @@ class DateConverter extends BaseCustomConverter implements ICustomConverter {
     String? format = getConverterParameter('format', jsonProperty);
     return format != null ? DateFormat(format) : null;
   }
-}
+}

mapper/lib/src/model/converters/default_converter.dart

@@ -39,4 +39,4 @@ class DefaultConverter implements ICustomConverter {
 
   @override
   dynamic toJSON(Object? object, SerializationContext context) => object;
-}
+}

mapper/lib/src/model/converters/default_iterable_converter.dart

@@ -71,4 +71,4 @@ class DefaultIterableConverter extends BaseCustomConverter
   void setIterableInstance(Iterable? instance) {
     _instance = instance;
   }
-}
+}

mapper/lib/src/model/converters/duration_converter.dart

@@ -18,4 +18,4 @@ class DurationConverter implements ICustomConverter<Duration?> {
   dynamic toJSON(Duration? object, SerializationContext context) {
     return object?.inMicroseconds;
   }
-}
+}

mapper/lib/src/model/converters/enum_converter.dart

@@ -31,4 +31,4 @@ class EnumConverter implements ICustomConverter, ICustomEnumConverter {
   void setEnumDescriptor(IEnumDescriptor? enumDescriptor) {
     _enumDescriptor = enumDescriptor;
   }
-}
+}

mapper/lib/src/model/converters/enum_converter_numeric.dart

@@ -49,4 +49,4 @@ class EnumConverterNumeric implements ICustomConverter, ICustomEnumConverter {
   void setEnumDescriptor(IEnumDescriptor? enumDescriptor) {
     _enumDescriptor = enumDescriptor;
   }
-}
+}

mapper/lib/src/model/converters/enum_converter_short.dart

@@ -71,4 +71,4 @@ class EnumConverterShort implements ICustomConverter, ICustomEnumConverter {
   dynamic _mapValue(dynamic value, Map mapping) => mapping.containsKey(value)
       ? mapping[value]
       : value.toString().split('.').last;
-}
+}

mapper/lib/src/model/converters/map_converter.dart

@@ -70,4 +70,4 @@ class MapConverter
   void setMapInstance(Map? instance) {
     _instance = instance;
   }
-}
+}