Support fs-verity signature in installer session

Known files (e.g. base apk, split apks and dex metadata) in installer
session can now be optionally installed with fs-verity signature
(PKCS#7) stored in the corresponding file with addional extension of
".fsv_sig".

For example, fs-verity signature files of foo.apk of foo.dm are
foo.apk.fsv_sig and foo.dm.fsv_sig, respecitvely.

Test: adb install-multiple with .fsv_sig
      # with change in adb to accept .fsv_sig, see the setup happened
Test: adb install-multiple with missing .fsv_sig
      # failed as expected
Test: atest com.android.cts.dexmetadata.InstallDexMetadataHostTest
Test: atest android.appsecurity.cts.SplitTests  # same pass/fail
Test: atest com.android.cts.apkverity.ApkVerityTest  # test WIP
Bug: 112037636
Change-Id: I109f580f637f1f538d0bf0bfacb499702dd72937