Add support for field split get/set declaration

[MangelMaxime]

TypeScript documentation:

export declare class Logger {
    get logHandler(): string;
    set logHandler(val: string);
}

translates into

type [<AllowNullLiteral>] Logger =
    abstract logHandler: string with get, set

Note

Add supports even if only one variation is provided

Example of npm package using this features:

@firebase/logger