[WebviewView] Ability to "show" via API

[GordonSmith]

Testing #105764

When hosting the WebviewView in a "Panel" we should be able to "show" it via API, in my example below:

1. User clicks an item in a custom TreeDataProvider.
2. I update the content and title of the WebviewView (title does not update see: [WebviewView] Changing Title When webviewView.visible === false #106083)
3. I would like to force "show" the WebviewView panel.

For comparison the vscode.Terminal has show and hide methods.

[GordonSmith]

Workaround:

    vscode.commands.executeCommand("WEBVIEW_ID.focus");

[GordonSmith]

@mjbvz how do you "show" a WebviewView which has not been resolved yet?

It feels like we should be able to resolve the hosting panel and "show" it?

[mjbvz]

You can use the command for that. We don't want to activate the extension that provides the webview until the view itself needs to be rendered