Move away from Webview UI Toolkit for Visual Studio Code

[FedericoPonzi]

The Webview UI Toolkit for VS Code will be deprecated on January 1, 2025. See the deprecation announcement for more details.

https://github.com/microsoft/vscode-webview-ui-toolkit

Not sure how urgent or complicated it would be. An alternative from the thread linked above: https://github.com/vscode-elements/elements