odb: rename `read_object_with_reference()`

odb: rename `read_object_with_reference()`

Rename `read_object_with_reference()` to `odb_read_object_peeled()` to
match other functions related to the object database and our modern
coding guidelines. Furthermore though, the old name didn't really
describe very well what this function actually does, which is to walk
down any commit and tag objects until an object of the required type has
been found. This is generally referred to as "peeling", so the new name
should be way more descriptive.

No compatibility wrapper is introduced as the function is not used a lot
throughout our codebase.

Signed-off-by: Patrick Steinhardt <ps@pks.im>
Signed-off-by: Junio C Hamano <gitster@pobox.com>