Implement 3PID Binding Hook for Pending Invites in bind.ts

[rezk2ll]

Description:

In the file packages/matrix-identity-server/src/3pid/bind.ts, there is a TODO comment on line 81 that needs to be addressed:

// TODO : hook for any pending invite and call the onbind api : https://spec.matrix.org/v1.11/client-server-api/#room-aliases

Problem:

The current implementation lacks functionality to handle pending invites and call the onbind API as specified in the

Tasks:

Create Long-Term Key Pairs:

• Generate long-term Ed25519 key pairs for signing purposes.

Create Signature:

• Implement a function to create a signature using the generated key pair.

• Make a POST request to /_matrix/identity/v2/sign-ed25519 to sign the data.

Call onbind API:

• matrix spec

• Implement a function to send a PUT request to /_matrix/federation/v1/3pid/onbind on the recipient's Matrix server.

• Ensure the request includes the necessary payload, such as the signed data and relevant 3PID information.