Treat non-integer target SDK as version 10000

Currently aapt2 treats non-integer target SDK values as SDK level 0.
This resulted in incorrect implied permission dumps. This change
causes aapt2 to treat non-integer SDK values as version 10000.

Bug: 155391001
Test: aapt2 dump badging CtsSkQPTestCases.apk
Change-Id: Ie4312a827974a7a10b40b12f8f23d264d1b1999a