Add lsp-restoration identity(ies) to RFC8776-bis

[ju7ien]

So far, tunnel models don't include any actual way to point to "full LSP rerouting" as a restoration-scheme, i.e. without any pre-X option. We need to be able to specify that an LSP can be restored without any preinstalled state before failure (cf. RFC 4872).

[italobusi]

See WG LC comment in https://mailarchive.ietf.org/arch/msg/teas/6AhyY7_rReueG12ZQylIOgpDJ9w/

[italobusi]

See proposed resolution in https://datatracker.ietf.org/meeting/118/materials/slides-118-teas-sessa-04-common-yang-data-types-for-traffic-engineering-01.pdf

[italobusi]

@tsaad-dev : in draft-ietf-teas-yang-te-35 the default value for the restoration-type has been removed but the default value for the restoration-sheme has not been removed

[italobusi]

Closed with 58a7811