[lib] Expand RoleInfo to LegacyRoleInfo | MinimallyEncodedRoleInfo

Summary:
Part of https://linear.app/comm/issue/ENG-6366/rename-minimallyencodedrawthreadinfo-to-rawthreadinfo

Depends on D10730

Test Plan: flow, done automatically with IDE "Inline alias.." refactor

Reviewers: ashoat, ginsu, tomek

Reviewed By: ashoat

Differential Revision: https://phab.comm.dev/D10731