Add 'current animator scale' to ApplicationSharedMemory.

The `getCurrentAnimatorScale()` binder call is on the critical path
during app-launch. On WearOS, the call latency is 7.8ms at p95, and
37ms at p99 (across all pixel devices: 1.4ms and 7ms respectively).
But this information can be shared across all processes (i.e. no
permission checks required), and is simple enough that it can be shared
via ApplicationSharedMemory, and thus avoid this binder call altogether.

Data: go/apc-bl-current-animator-scale

Flag: com.android.window.flags.current_animator_scale_uses_shared_memory
Bug: 406182390
Test: atest ApplicationSharedMemoryTest

Change-Id: I42bee3534336ecef69a1dbde8a42ccb13d9b1e48