fix: add typescript definitions

[steve3d]

Because I'm just a user of fancybox 4, so I did not know much of core design of this package. These definitions are created by tsc and manually edited by me. So before actual merging, you might need to review and modify some of definitions, to determine how many or what functions are exposed in these typescript definitions.

and BTW, thanks for this great package.

[jacobgraf]

We absolutely love Fancybox 4, but had to give it up and move to Headless UI due to the lack of TypeScript support. I'll keep an eye on this and hopefully in the future we will be able to come back. TypeScript support is a make/break these days, unfortunately.

[fancyapps]

Hi, Thank you for your work, typescript definitions are available in v5.