Preview URLs: Client-side previewOption extension kind

[leekelleher]

Note

This pull request has been developed on top of #20021, with a view to merge this into that, to have a PR contain a single unified feature.

Description

Introduces a previewOption kind for the workspaceActionMenuItem extension-type. This will enable a 3rd-party implementation to define a custom preview option for their own target preview environment, (using a server-side registered IUrlProvider, see #20021 for further details).

The default "Save and preview" action has been refactored to make use of the new extension kind.

How to test?

Initially, test that the built-in "Save and preview" action/button still works as expected.

Next, try adding a custom previewOption extension kind...

{
	type: 'workspaceActionMenuItem',
	kind: 'previewOption',
	alias: 'My.Custom.PreviewOption',
	name: 'My Custom Preview Option',
	forWorkspaceActions: 'Umb.WorkspaceAction.Document.SaveAndPreview',
	weight: 101,
	meta: {
		icon: 'icon-umbraco',
		label: 'Preview.me',
		urlProviderAlias: 'MyUrlProvider',
	},
}

Notice that the custom preview option replaces the core "Save and preview" button (moving it an addition workspace-action-menu-item). This is configurable by the weighing, the core option is weighted at 100.

If the custom URL provider has not been registered on the server, then pressing the action in the result in an error, (the message is provided by the server).

With a custom IUrlProvider registered on the server, the target URL of the preview environment will be returned and a new tab/window will be opened for the user.