Android: Rework settings dialog

Make it possible to create multiple AndroidConfigs so that we can have
a different one in the settings dialog from the global one. Move pretty
much every method from AndroidConfigurations to AndroidConfig, so that
the settings dialog can work with its copy. Also add some additional
logic to the settings page around the java setting. To start the avd
manager we need both a sdk path and a java path. Also do some basic
additional checking of the java path.

Task-number: QTCREATORBUG-7724
Task-number: QTCREATORBUG-10936
Task-number: QTCREATORBUG-10937
Task-number: QTCREATORBUG-11059
Task-number: QTCREATORBUG-11218
Change-Id: I148c69b9c98a8a070d17d9b0e223d01db1750e69
Reviewed-by: Daniel Teske <daniel.teske@digia.com>