[Task] Expose DID trait in bindings.

[HenriqueNogara]

Description

Expose DID trait in bindings.

Motivation

Allow users to add their custom DID implementation.

[cycraig]

~The comment https://github.com/iotaledger/identity.rs/pull/968#discussion_r940741266 was specifically on adding the DID trait methods to the WasmCoreDID struct (scheme(), authority(), method(), etc.) to match the methods of WasmIotaDID and WasmStardustDID. It's still unclear how we would achieve custom DID implementations in Wasm.~

Added missing CoreDID and DID trait methods to WasmCoreDID in #994.

[eike-hass]

Solved in #994.