Added Typescript Support for Storyblok Bridge

[imabp]

I have added typescript support for Storyblok Bridge.
The code implements Declaration merging with global class which helps to fulfill the requirement for useStoryblok hook in a typesafe way.

This is being tried and tested here

[imabp]

👋 Hey @fgiuliani @alexjoverm .
Please review and merge 😊

[alexjoverm]

Hey @imabp, to add full Typescript integration will require more work. Let me give you a few pointers:

• We prefer having the source code in Typescript. In that way, types are autogenerated, better typed, and easier to maintain
• Types can be more sophisticated/elaborated
• More steps are needed to integrate Typescript (like a few changes in package.json) and we'd rather keep it in 1 PR since is not much work

So we can't accept this PR as it is now, but if you feel like these changes is something you can and want to do, feel free to go for it.

[imabp]

Thank you so much @alexjoverm !!
I was also thinking the same, so we can extend support for both the languages.
I have created a new issue for migrating to typescript: #4

Feel free to assign the work, would love to work on it!

[patsimm]

@alexjoverm I tried to apply the points you had in #13.