Move Pip codes from SysUI to WMShell lib (9/N)

Bug: 161118569

Test: make SystemUI
Test: make ArcSystemUI
Test: make WMShellUnitTests
Test: lunch cf_x86_tv-userdebug & make
Test: atest CtsSystemUiTestCases:BasicPipTests
Test: atest CtsSystemUiTestCases:CustomPipActionsTests
Test: atest CtsSystemUiTestCases:FlickerPipTests
Test: atest CtsSystemUiTestCases:PipNotificationTests
Test: atest SystemUITests
Test: atest WMShellUnitTests
Test: manual test PIP demo AP
Test: manual test TV PIP function
Test: manual test disabled PIP
Test: adb shell input keyevent 171(KEYCODE_WINDOW)
Test: adb shell am start -n android.systemui.cts.tv.pip/.PipTestActivity
    -a android.systemui.cts.tv.pip.PipTestActivity.enter_pip
Test: adb root;adb shell am start \
    -n com.android.systemui/com.android.wm.shell.pip.tv.PipMenuActivity
Test: adb shell dumpsys activity service com.android.systemui
Change-Id: I0ec0e9b9bfc4795a10483acd225f14bde9c72407