settings command delete by user

bug: 118492733
Test: $ adb shell settings --user 10 put secure autofill_service blah
$ adb shell settings --user 10 get secure autofill_service
blah
$ adb shell settings --user 10 delete secure autofill_service
$ adb shell settings --user 10 get secure autofill_service
null

Change-Id: I771bf8e148898703332ead8162c5f9fe4863ea74
3 files changed