Allow widgets to create rooms and spaces

### Your use case

#### What would you like to do?

As a widget developer I want to create rooms and spaces from a widget.

#### Why would you like to do it?

A widget could support the user in creating more complex space and room structures for purposes like events, conferences or bar camps.

#### How would you like to achieve it?

We want to access the create room endpoint using the `matrix-widget-api`

### Have you considered any alternatives?

_No response_

### Additional context

_No response_