Support lazy activation

These are the current activation events:

Basically, the extension is always active. However, I don't think the extension does much when it does not actively show a browser and I imagine many users dont use this extension every day (even though this extension brings an amazing value to VS Code).

If you could remove all these activation events and only activate when webviews are restored or the user explicitly starts a launch target or triggers a command to open a new webview/a preview, that would improve the startup time for millions of users.
It would also reduce the memory pressure of all these users and allow for immediate extension updates, as extensions which have not been activated yet can be updated without restarting VS Code.

Start by inspecting the extension's activation events and the entry points for restored webviews, launch targets, and commands that open a new webview or preview. Confirm which activation paths are still required and verify that the extension remains inactive until one of those paths is used, while preserving the existing webview and launch behavior.