Postpone initialization of FakerConfig through the Builder

[serpro69]

val configBuilder = FakerConfig.Builder()
    .setLocale("nl")
    .setUniqueGeneratorRetryLimit(111)

configBuilder.setRandomSeed(42)

val config: FakerConfig = configBuilder.build()

val faker = Faker(config)

The above is currently not supported because:

• FakerConfig.Builder has internally-visible constructor
• setter functions need to be added that return an instance of Builder

Motivation:

• There could be situations where one might want to postpone building the config instance, this is not possible with the fakerConfig function that builds the FakerConfig instance automatically.
• This is a more natural way to do builders in java (Lambdas in java are also quite ugly.) and could be preferable to usage of fakerConfig function.