[lib] Rename getRolePermissionBlobsForCommunity to getRolePermissionBlobsForCommunityRoot

Summary:
Just a small rename since this function is only for community roots

Depends on D9900

Test Plan: flow

Reviewers: atul, ginsu, ashoat

Reviewed By: ashoat

Subscribers: ashoat, tomek

Differential Revision: https://phab.comm.dev/D9901