OAuth2 VSCode

[isc-klu]

This PR refactors authentication throughout the extension to use the Authorization class from @intersystems-community/intersystems-servermanager instead of directly managing username/password strings.

Key changes:

• Replace username/password properties with Authorization type in connection configurations
• Use auth.username and auth.accessToken instead of direct credential access
• Leverage auth.resolve() and auth.httpAuthorizationHeader for authentication checks
• Update REST debug panel and WebSocket terminal to use authorization methods
• Remove isUnauthenticated() helper in favor of auth.resolved() checks
• This improves security by centralizing credential handling through Server Manager's authorization abstraction and prepares the codebase for future OAuth2 support.

[isc-bsaviano]

Does this code block (and others) need to be able to handle the OAuth case where there is no username?

[isc-klu]

Currently, when auth is OAuth2, the username is hardcoded to "OAuth2User". Is this behavior okay?