Add APPENDCONFIG to android Extras

First and foremost consider this:

• Only RetroArch bugs should be filed here. Not core bugs or game bugs
• This is not a forum or a help section, this is strictly developer oriented

Description

The current android implementation only includes the following extras, as shown here (comments below on the values are mine)

  -e ROM {file path}. #Required
  -e LIBRETRO {core path} #Required
  -e CONFIGFILE {config file path} #Required
  -e IME com.android.inputmethod.latin/.LatinIME #Standard android fluff as far as i can tell, and its required otherwise the app wont launch
  -e DATADIR /data/data/com.retroarch  #What is this needed for, if at all?
  -e APK /data/app/com.retroarch-1/base.apk   #What is this needed for, if at all?
  -e SDCARD /storage/emulated/0 #What is this needed for, if at all?
  -e EXTERNAL /storage/emulated/0/Android/data/com.retroarch/files  #What is this needed for, if at all?

At a minimum, it would be nice if APPENDCONFIG could be added as an extra, to allow for modification of the configuration on launch from a different front end.
Even better would be to include the command line options, where possible, that are included in the standard windows or linux environments.

Expected behavior

Additional configuration options in RA available in Android

Actual behavior

Limited configuration options in RA available in Android

Steps to reproduce the bug

NA

Bisect Results

It's always been this way.

Version/Commit

You can find this information under Information/System Information

• RetroArch: 1.9.0 or older

Environment information

• OS: Android (any)
• Compiler: N/A

Start with pkg/android/phoenix-legacy/src/com/retroarch/browser/mainmenu/MainMenuActivity.java at the referenced extras handling. Determine how APPENDCONFIG should be exposed when launching RetroArch and which additional command-line options, if any, are in scope; done means Android launches can receive the requested configuration options.