Add android.hidl.token@1.0::ITokenManager impl.

For now, this service will be part of hwservicemanager because it is
also for registration and unregistration of services. There are a couple
main differences between IServiceManager and ITokenManager:

- IServiceManager keeps strong references to interfaces, but ITokenManager
  keeps week references.
- IServiceManager receives the token (name) of an interface, but
  ITokenManager creates and returns tokens to things registering
  themselves.

Test: hidl_test passes:

make hidl_test hwservicemanager -j64 && adb sync && phone-kill
hwservicemanager && adb shell ./data/nativetest64/hidl_test/hidl_test64

(where phone-kill kills a process on my phone. hwservicemanager will
automatically restart)

Bug: 33058559
Change-Id: I09741aa99edb7c2c97ffc057c7ff71d9d9dabc02
4 files changed