Add option in composer to autoformat selected lines as markdown list

### Your use case

#### What would you like to do?
I would like to be able to select lines of text and format these as a list without having to manually prepend `- `, `+ ` or `1. ` on every line.

#### Why would you like to do it?
Bulleted and numbered markdown lists are supported by commonmark and are often used at my work. Element's editor/composer already features most of the other commonmark formatting options as buttons and shortcuts and I believe having this for lists as well would be convenient to users.

#### How would you like to achieve it?
By adding the functionality and related buttons and shortcuts to the composer:

https://user-images.githubusercontent.com/94838646/197222015-1a3d047e-aff9-47ce-a0a1-9fc96434389c.mov

### Have you considered any alternatives?

_No response_

### Additional context

I already did some work on this: https://github.com/matrix-org/matrix-react-sdk/pull/9473
It is mainly missing the correct button icons and might feature shortcuts which are not compatible with every browser.