[SB][RON] Add custom color to RON demo command.

Bug: 361346412
Flag: com.android.systemui.status_bar_ron_chips
Test: `adb shell cmd statusbar demo-ron -p com.android.systemui -t 10min -c 434343`
-> verify status bar chip shows with dark gray color
Test: verify call chips and screen share chips still work as expected
Test: atest DemoRonChipViewModelTest

Change-Id: I5765c83ba2038d8c9a07ef48ba4c2dab151c6c24