[Feature] Manually declare slots/events

[Nick-Mazuk]

Describe the bug

Currently, this plugin doesn't support TypeScript (#4). This means it doesn't automatically detect props/slots/events.

While you can manually declare props via the argTypes prop on the Meta component, I don't believe you can manually add slots or events. Could be mistaken, though.

While full TypeScript support is preferable, I believe being able to manually declare slots is also a good option to be able to future-proof the addon.

[j3rem1e]

Typescript supports is not necessary to detect events and slots.

Storybook uses sveltedoc-parser which supports this properties. look at the officiel svelte kitchen sink.

[benbender]

@j3rem1e Automatic typed CustomEvents are now available in Svelte. See sveltejs/language-tools#424 (comment). Would be nice to reopen this and have them supported.