Updater: Show update's version wherever applicable

Currently at most of the places, build version is obtained from BuildInfoUtils.getBuildVersion()
method. This method obtains build version from the current running system's property.

At /e/, we bump version number on every new OTA. This results in version mismatch in several places
in the updater app. Let's get the version from the update itself to show the proper version.

Signed-off-by: Aayush Gupta <theimpulson@e.email>
Change-Id: Ia74085d8d7c067c408e7cfce1de90d49dcc68307