Delay frozen app sockets close until the cellular modem wakes up

Closing TCP sockets sends RST packets. If the cellular modem is idle,
sending RST packets will wake the modem up and consume battery.

This CL adds delay_destroy_frozen_sockets_version flag.
When this flag and destroy_frozen_sockets_version is enabled,
ConnectivityService delays closing socket until the cellular modem wakes up.
Pending frozen sockets are closed also when cellular network becomes no
longer the default network.

This CL also adds flag status and pending uids to the dump.

Bug: 284900338
Test: FrameworksNetTests
Change-Id: I2562568390dda36d02f72afb3a96f824788964c0