Svelte package migration

[mhkeller]

This updates the npm run package process to use the new svelte-package library. It defines exports and typesVersions.

[mhkeller]

Tagging some Layer Cake typescript users to see if this package.json is set up correctly. If you could take a look and see if this is the easiest way to set up the exports and types, I would appreciate it: @abalmos, @techniq, @allezxandre

I am using the typesVersion option as described here but perhaps a better way to do it is to add documentation saying people need to:

set the moduleResolution option in their tsconfig/jsconfig.json to bundler (available since TypeScript 5, the best and recommended option in the future), node16 or nodenext.

Let me know if you have thoughts on what is currently easiest for typescript users.

[allezxandre]

Sorry, I can't be of much help here, I've always used the default settings with TypeScript code, so I wouldn't know how integrating your own type definitions would work 😕