Teach appt2 to handle <required-(not-)feature>

Introducing 'required-feature' and 'requred-not-feature' tags that could
be used "inside" 'uses-permission' elements.
Elements of both types should have non-empty 'android:name' attribute to
specify the name of the feature.

Bug: 168079571
Test: make aapt2
Test: make aapt2_tests
Test: out/host/linux-x86/nativetest64/aapt2_tests/aapt2_tests
Test: create AndroidManifest.xml with <required(-not)-feature>
Test: aapt2 link -o out.apk -I $ANDROID_SDK/platforms/android-30/android.jar --manifest AndroidManifest.xml
Test: aapt2 dump badging out.apk
Test: appt2 dump permissions out.apk
Change-Id: I67ba0731daa6d31cd976b922217853f159cf7c3a