Publish vscode types

We are using @types/vscode for publishing vscode.d.ts. See https://github.com/Microsoft/vscode/issues/70175 for details.

For each release, we will need to publish a new version to DefinitelyTyped. Here are the steps:

1. When you publish a tag such as 1.34.0
2. CI creates a branch vscode-types-1.34.0 at https://github.com/DefinitelyTyped/DefinitelyTyped with commit message VS Code 1.34.0 Extension API.
3. CI sends a link to create PR to #release channel of VS Code Slack.
4. Ask either @octref, @jrieken, @kieferrm or @egamma to merge the PR.
5. @types/vscode will be published in ~10 minutes.