bfdd: add bfdname in bfd_key

bfdd: add bfdname in bfd_key

sbfd will use bfdname for key hash, We introduced a bfd-name for every sbfd session, normal BFD sessions can leave it as NULL.
A unique bfd-name can be used to identify a sbfd session quickly. This is quite useful in our Srv6 deployment for path protection case.
For example, if use the sbfd session to protect the SRv6 path A-B-D, we would assign the name 'path-a-b-d' or 'a-b-d' to the session.

Signed-off-by: wumu.zsl <wumu.zsl@alibaba-inc.com>