Limit the number of supported v1 and v2 signers

The v1 and v2 APK Signature Schemes support multiple signers; this
was intended to allow multiple entities to sign an APK. Previously,
the platform had no limits placed on the number of signers supported
in an APK, but this commit sets a hard limit of 10 supported signers
for these signature schemes to ensure a large number of signers
does not place undue burden on the platform.

Bug: 266580022
Test: Manually verified the platform only allowed an APK with the
       maximum number of supported signers.
Change-Id: I6aa86b615b203cdc69d58a593ccf8f18474ca091