[lib] Propagate MEMBER permissions to all chats in a community

Summary:
This addresses ENG-9054.

The issue is that in D13014, I return false from includeThreadPermissionForThreadType even if a propagation prefix is set.

We want role permissions to apply to all chats in a community, even if there is a "broken link" where you are a member of a grandchild but not a member of its parent.

Depends on D13112

Test Plan:

1. I set up a repro of the issue in my local environment
2. I applied this diff to fix the issue
3. I reset db_version to 67 to trigger migration 68 again
4. After migration 68 ran again, I confirmed that the issue was gone

Reviewers: tomek, inka

Reviewed By: tomek

Differential Revision: https://phab.comm.dev/D13113