Add HttpResponseCacheTest as a CTS test

Moving HttpResponseCacheTest.java from
frameworks/base/core/tests/coretests/src/android/net/http
to
cts/tests/tests/net/src/android/net/http/cts

And making it work in the CTS runner by setting
temp directory permissions and making sure the
cache is initialized.

Change-Id: I032014789f27a66c1a7a0aee0fa0494f6041238e