How to add back default annotations for the "block" field marks?

[mitchuman]

Is your feature request related to a problem? Please describe.
Is there a way to pull the default values for annotations for the block type (aka. richtext/portable text field)?

Describe the solution you'd like
I don't want to have to recreate the existing "link" annotation from scratch each time I add a new custom annotation.
Ideal solution (or something of the likes):

{
  type: 'block',
  marks: {
    annotations: [
      ...defaultAnnotationsEtc(), // 👈 here
      myCustomAnnotation,
    ]
  }
}

Describe alternatives you've considered
I had attempted to recreate the default "link" annotation using an href string field but the Input popover component in the Studio stretches wider than what the default looked like. Additionally, the validation was behaving weird too where it didn't accept internal URLs (starting with /).

Additional context
Add any other context or screenshots about the feature request here.