Add a version check in CaptivePortalLoginActivityTest

- Add comments to describe why version check is needed.
- Add a version check in CaptivePortalLoginActivityTest.
- Set jni_uses_sdk_apis to use portable JNI libraries.

Bug: 168567727
Test: 1. atest CaptivePortalLoginActivityTest
      2. Run CaptivePortalLoginActivityTest on both of Q & R
         devices.
         For Q device, the testVpnMsgOrLinkToBrowser_BeforeR()
         will be run.
         For R device, the testVpnMsgOrLinkToBrowser() will be
         run.
Change-Id: Icc69240e02b8d22fc9f5b0b61edaff0afbed67d8
3 files changed