Allow {#...} and {@...}

[Refzlund]

While Svelte (or typescript) will throw an error when we don't close the statements (such as #if #each #await) — we can still just close them.

From what I've noticed, this may or may not provide types for awaited promises and each iterated items which are a major reason to work on this feature.

I will look for closing statements (/if /each etc.) and remove them. This makes it compatible to not have them in the first place, if we one day don't get the error </template> attempted to close an element that was not opents(-1) anymore.

I will work on this next week or sometime in February🕺🦒
If you want to contribute to this enhancement let me know👏