Android: Give user the option for selecting browser for HS 2.0 OSU

Android: Give user the option for selecting browser for HS 2.0 OSU

When built with browser-android.c, hs20-osu-client used to always launch
the native/stock Android browser for OSU user interaction. This browser
is not present in all devices. It is better to give the option to the
user to select his/her browser.

Here the user will be shown a pop up to select the browser that he/she
wants.

Signed-off-by: Somdas Bandyopadhyay <somdas.bandyopadhyay@intel.com>