Support Share as > Copy vscode.dev link in RemoteHub repositories

[joyceerhl]

In desktop GitHub repos we have the ability to do File > Share as > Copy vscode.dev link, and also to right click on an open editor and do Share as > Copy vscode.dev link. From microsoft/vscode#157722 (comment) we also want this functionality. As a stopgap until we have generic extension API for getting the current repository info, we also contribute this functionality in RemoteHub.

Verification:

• Install GitHub.remotehub and ms-vscode.azure-repos
• Open a GitHub repository or Azure Repos repository in desktop via Open Remote Repository
• Ensure that you have the Share as > copy vscode.dev link action in the file and editor context menu
• Generated links should align with the links created in desktop, including preserving editor selection and notebook cell deeplinks