Report all errors with hidden API flags not just the first one

Previously, if an error in a flag was found the process (hiddenapi or
veridex) would exit immediately. That made it necessary to iteratively
fix the source of the error, rerun the build, wait to see if it fails
again, if it does repeat.

This change logs all errors with flags found while parsing a specific
file and only then exits.

Bug: 253335210
Test: build/soong/soong_ui.bash --make-mode TARGET_PRODUCT=aosp_cf_x86_64_phone TARGET_BUILD_VARIANT=userdebug droid dist
Change-Id: Ie13bcc2362ce9986c9958d8f31d72999f4559c06
(cherry picked from commit 862cf7dbff31d4066f81b0d007f677977ffcb9cd)
Merged-In: Ie13bcc2362ce9986c9958d8f31d72999f4559c06