Use fluent API for adding webhook events and add document type events

[ronaldbarendse]

Prerequisites

• I have added steps to test this contribution in the description below

Description

Extending on PR #15344, this makes adding webhook events use a (nested) fluent API, so adding only content events can be done the following way:

using Umbraco.Cms.Core.Composing;

public class WebhookComposer : IComposer
{
    public void Compose(IUmbracoBuilder builder)
        => builder.WebhookEvents()
            .Clear()
            .AddCms(cmsBuilder => cmsBuilder.AddContent());
}

Similarly, adding all events can be done using builder.WebhookEvents().AddCms() or just user login events using AddCms(cmsBuilder => cmsBuilder.AddUser(userBuilder => userBuilder.AddLogin())).

Other products and packages could use a similar structure, e.g. AddForms(), AddDeploy() and AddCommerce()... And if we add more events of a specific type, a nested fluent API can be easily created by adding a new overload that accepts the Action<FluentBuidlerTypeName>.

[Zeegaan]

Love this approach, just needs proper documenting 🙈
I have a task this sprint for documenting, so noting this down 👍

[nul800sebastiaan]

@Zeegaan @ronaldbarendse Ping me when this is merged and then I can fix up #15337 and merge it as well 👍