fun loadBirthdayFromAssets(context: Context, birthdayHeight: Int? = null): WalletBirthday
Load the given birthday file from the assets of the given context. When no height is specified, we default to the file with the greatest name.
context - the context from which to load assets.
birthdayHeight - the height file to look for among the file names.
Return
a WalletBirthday that reflects the contents of the file or an exception when
parsing fails.