[proposal]Support for authentication methods based on the W3C DID specification did:wba

[chgaowei]

Based on your changes, I added an experimental authentication method. I hope you can help me review it.
There’s no need to merge it into your branch for now. Once your branch is merged, I will submit a PR. Thanks!

Motivation and Context

We have added an experimental authentication scheme, did:wba, to MCP.

We believe did:wba can serve as an excellent complement to OAuth 2.0 for the following reasons:

1. did:wba provides security equivalent to OAuth 2.0.
2. did:wba supports decentralized identity authentication, offering better interoperability.
3. did:wba requires fewer interactions and has a simpler process.

The changes in this code are based on a branch that has not yet been merged into the main branch (PR link: modelcontextprotocol#101). We will update our code accordingly if there are any changes to this branch.

How Has This Been Tested?

This proposal has not yet been implemented in a client/server.

Breaking Changes

Users do not need to update their code or configuration. As an experimental scheme, the server or client can choose not to support it.

Types of changes

• Bug fix (non-breaking change which fixes an issue)
• New feature (non-breaking change which adds functionality)
• Breaking change (fix or feature that would cause existing functionality to change)
• Documentation update

Checklist

• I have read the MCP Documentation
• My code follows the repository's style guidelines
• New and existing tests pass locally
• I have added appropriate error handling
• I have added or updated documentation as needed

Additional context

Relevant documentation links:

1. did:wba Method Design Specification

2. blogs：

• did:wba - A Web-based Decentralized Identifier
• Security Principles of did:wba
• The Most Suitable Identity Authentication Technology for Agents: Comparing OpenID Connect, API Keys, and did:wba

[k6l3]

@chgaowei Thanks! I'll push to get this PR landed soon, appreciate your proposal here.