Set child process name with child zygote args

When forking zygote processes, 'forkSimpleApps' may process multiple
simple apps in the command buffer at once. However, the parsed zygote
arguments are computed based on the first app in the command buffer,
which can lead to all launched processes being assigned the same name.

Move the setting of the child process name into childMain and use the
arguments from it's local ZygoteArguments for the appropriate name.

Bug: 305970538
Test: Verified aosp_cf_riscv64_phone correctly uses unique process names
and PIDs match intended name.
Change-Id: I0febc49649b0ede4c07898b47b0ebe6ac37e7057

Change-Id: I64b2644ffb8ee75043623222b48fba8f2cfc5f08