[feature] Option to configure line breaks

[NebelNidas]

Currently, JADX hardcodes the the system default for line breaks. In certain situations, it may be desirable to define a specific one though. This is something I wouldn't necessarily expose via JadxArgs, but it should be possible to overwrite the default value in ICodeWriter by using a custom implementation thereof. If you could change NL from being a field to an interface method, like nl(), which can be overridden, that would be much appreciated.

[skylot]

Done, now it is possible to set new line string in JadxArgs:

args.setCodeNewLineStr("\n");