`UpdateScripts` should have `$this->addon`

[edalzell]

Bug description

In an update script you often want to do "addon" things like update the setting, etc.

Right now you have to do this:

Addon::get('transformstudios/events')
    ->settings()
...

Would be great if there was a property $addon we could reference.

How to reproduce

N/A

Logs

Environment

N/A

Installation

Fresh statamic/statamic site via CLI

Additional details

No response