Support dynamic 64-bit drmserver

64-bit GSI requires support both 64_32-bit and 64-bit devices at
the same time. Add a new variable TARGET_DYNAMIC_64_32_DRMSERVER
to put drmserver_dynamic.rc into GSI. Which starts 64-bit
drmserver if ro.zygote is zygote64. Otherwise, it keeps the
original behavior to start 32-bit drmserver.

Bug: 282603373
Test: make gsi_arm64-user; Check system/etc/init
Test: make gsi_arm-user; Check systen/etc/init
Change-Id: I874cee00a066086f565e044549ad40c6ab5d62b0
Merged-In: I874cee00a066086f565e044549ad40c6ab5d62b0