Updated v4 signature processing.

Passing to libincfs.so.
Obtaining and verifying, including v3 digest check.

go/apk-v4-signature-format

Test: atest PackageManagerShellCommandTest
Bug: b/151241461
Change-Id: Id61f5716b9f9b55d6ab1ebca5a7ecb1c6e54570a
11 files changed