Support multi-display screenshot in dumpstate

Added a flag -m to dumpstate which takes screenshots of all displays
and provides a zip file including them instead of a single png file.

This feature is available only when
bugreport_multi_display_screenshot_enabled flag is enabled.

Bug: 364767133
Test: Build and Run `dumpstate -p -m`
Flag: android.os.bugreport_multi_display_screenshot_enabled
Change-Id: I2705ab478edbd96042fd7130b0a2b14750dc21a0