Implement firewall status bar indicator

* Add API to get the last resumed activity's UID
* Show blocked status indicator based on the last resumed activity's UID blocked status

Also includes squashed changes:

Author: Michael Bestas <mkbestas@gmail.com>
Date:   Thu Mar 2 01:01:37 2023 +0200

    fixup! Implement firewall status bar indicator

    Adding new core symbols is a no go, we can still make this work
    by moving the string to SystemUI. config_statusBarIcons is
    only used in StatusBarShellCommand for "get-status-icons" command.

    Change-Id: Ic4daaacb2b0db0b94fcd4aee0d7880a6b12c97b0

Author: Oliver Scott <olivercscott@gmail.com>
Date:   Tue Mar 14 15:32:06 2023 -0400

    fixup! Implement firewall status bar indicator

    Check UID network access when its default network changes.

    Issue: calyxos#1041
    Requires: I2729b61c349ec2812a74d7d1c04b90a58b0f5b88
    Change-Id: Ied0f465f485a4415ae50f4ffc50a4ce9b6caa25e

Co-authored-by: Michael Bestas <mkbestas@gmail.com>
Change-Id: I7aa405e7f5a2f70e6cf2b6156a29d220617e4ae5