Binding on-demand #7: PerformInitializeTask usage

Migrate transport initialization task to binding on-demand. Added
Robolectric tests for the task as well.

Bug: 17140907
Test: m -j RunFrameworksServicesRoboTest
Test: adb shell bmgr init <transport>, observed logs & transport dir
Change-Id: I2d6c1acd31741169080edef2f938fabf43b0649a