Move BLAST flag to WindowManagerService

Querying flag property in preloaded class static initialization
removes it from preloading and increases boot time.  Move query
to WindowManagerService instead when constructed

Bug: 148614188
Test: build, boot, adb shell device_config put
window_manager_native_boot wm_use_blast_adapter true/false
check that BLAST adapter is turned on/off as expected

Change-Id: I02e2327b5c2cb11a231d02fc2c5c8c1ac200aaf0