Add bufferSizeMs parameter to recorder interface

[ebraraktas]

This PR allows us to resolve this issue. It adds bufferSizeMs parameter to Android and iOS implementation. Hence, one can record to a stream with chunks having specific size.

[Larpoux]

Hi @ebraraktas ,

Thank you very much for your contribution.
I am really impressed by what you did. Coding inside flutter_sound_core is not easy because the library is not under pub.dev.
Congratulations.

Actually I am integrating your code inside the last flutter_sound version.
I have something wrong on Android : it seems that the end of the last buffer is not sent.
Maybe a problem inside writeData(). Or perhaps I did not report correctly your code inside flutterSound.
writeData() is hard to read. Is it possible that you look on it ?

Here is my FlautoRecorderEngine.java
FlautoRecorderEngine.java.txt

(its a .txt because github does not want to include a .java