getUniversalCommunityRootPermissionsBlob is going to emulate the way we construct permissions blobs so it's more extendible towards separating permissions included for all roles in both COMMUNITY_ROOT and COMMUNITY_ANNOUNCEMENT_ROOT.
I'm not completetly deleting universalCommunityPermissions in thread-permissions-types.js yet, but I will do that once I land this entire stack + rebase the stack starting at D9493, since otherwise it'll cause a ton of merge conflicts and broken unit tests.
The rest of this stack will update usages of universalCommunityPermissions besides the unit test with this new method.
Addressess ENG-5761
Depends on D9514