refs API: post-migration API renaming [1/2]

refs API: post-migration API renaming [1/2]

In preceding commits all callers of refs_resolve_ref_unsafe() were
migrated to the transitory refs_werrres_ref_unsafe() function.

As a first step in getting rid of it let's remove the old function
from the public API (it went unused in a preceding commit).

We then provide both a coccinelle rule to do the rename, and a macro
to avoid breaking the existing callers.

Signed-off-by: Ævar Arnfjörð Bjarmason <redacted>
Signed-off-by: Junio C Hamano <redacted>