[keyserver/lib/native] Introduce VOICED_IN_ANNOUNCEMENT_CHANNELS thread permission

Summary:
This diff introduces a new thread permission, VOICED_IN_ANNOUNCEMENT_CHANNELS. We also create a propgated/filtered version of this permission, `descendant_toplevel_voiced_in_announcement_channels.

The idea here is that if the user-surfaced VOICED_IN_ANNOUNCEMENT_CHANNELS permission is granted, we give the role both of these permissions. In makePermissionBlob, we can then grant voiced for an announcement thread in a really easy way.

I will be adding a updateRolesAndPermissionsForAllThreads migration once at the end of this entire stack, so that's why I didn't add it here

Addresses ENG-5785

Depends on D9901

Test Plan: I went through every step in my final testing task and was able to perform all the steps with expected results

Reviewers: atul, ginsu, ashoat

Reviewed By: atul, ashoat

Subscribers: ashoat, tomek, wyilio

Differential Revision: https://phab.comm.dev/D9827