Add the metalava_enabled property

The new property is added for supporting metalava. But some sdk library
cannot use metalava. So "metalava_enabled: false" is added to these
modules.

Test: make -j
Test: checkapi
Bug: 117127012
Merged-In: Ib65f3cd73dac0ac6ed64afeca6546d99739e4424
Change-Id: Ib65f3cd73dac0ac6ed64afeca6546d99739e4424
(cherry picked from commit 558e702b)