Add transform option to Ad4mModel properties

[lucksus]

Add transform option to property decorators

This PR adds a new transform option to property decorators in Ad4mModel, allowing property values to be transformed after they are retrieved from the perspective. This feature is particularly useful for converting raw data into more usable formats or applying custom transformations to property values.

Features

• Added transform option to PropertyOptions interface
• Transform functions are applied after value resolution in assignValuesToInstance
• Works with all property decorators (@Property, @Optional, @ReadOnly)
• Fully documented with examples
• Includes comprehensive test coverage

Example Usage

class ImagePost extends Ad4mModel {
  @Property({
    through: "image://data",
    resolveLanguage: "literal",
    transform: (data) => data ? data:image/png;base64,${data.data_base64} : undefined,
  })
  image: string = "";
}