Added command line tool to enable/disable new data stack

Provide the temporary command line tool to check whether new
data stack is enabled or not.

Bug: 196597630
Test: adb shell cmd phone get-data-mode
Change-Id: I9f95e7424e6e74af12a0f6780a58fb5732df7300
Merged-In: I9f95e7424e6e74af12a0f6780a58fb5732df7300
1 file changed