[lib] Rename getCachedEntryForAddress to getCachedNameEntryForAddress

Summary:
In a following diff, I'm going to introduce getCachedAvatarEntryForAddress, so I'm clarifying this method's name now.

For consistency, also renamed getCachedEntryForName to this.getCachedAddressEntryForName.

Test Plan: Flow

Reviewers: atul

Reviewed By: atul

Subscribers: tomek

Differential Revision: https://phab.comm.dev/D7039