Apply hiddenapi build tool on boot jars

Restrictions on usage of private APIs require encoding new information
into the dex files of the boot class path. ART now contains a new build
tool called `hiddenapi` which takes three lists of class member
signatures (blacklist, light and dark greylist), finds the class members
in their respective dex files and modifies their access flags in place.

This patch invokes the `hiddenapi` tool on all JARs in
PRODUCT_BOOT_JARS. For Java libraries built with Makefiles the tool is
invoked after the dexer directly on DEX files. For Soong-built
libraries, the build system has to unzip the JAR produced by Soong,
apply `hiddenapi` and rezip again. This is due to the fact that the
PRODUCT_BOOT_JARS variable is not available to Soong.

Bug: 64382372
Test: m
Change-Id: I6ce897d204459c8b6f46ed49e0909ff76c08a9ed