Fix types for composables

[BeeMargarida]

What package has an issue

@svelteuidev/composables

A clear and concise description of what the bug is

The custom events in composables are not being typed. There is a workaround to support this, see:

https://github.com/sveltejs/language-tools/blob/master/docs/preprocessors/typescript.md#im-using-an-attributeevent-on-a-dom-element-and-it-throws-a-type-error

In which browser(s) did the problem occur?

No response

Steps To Reproduce

Check use-move demo.

Do you know how to fix the issue

Yes

Are you willing to participate in fixing this issue and create a pull request with the fix

Yes

Relevant Assets

No response