feat: add typescript definitions

[d3v2a]

i think it's not perfect (i start using typescrypt one week ago) but it's a good starting point.

Utils, LocalStorage, SessionStorage is not done due lack of time ...

[igorgo]

I think that it is not necessary here.
There is a special project for such definitions - https://github.com/DefinitelyTyped/DefinitelyTyped.

[John0x]

@igorgo it would benefit everyone if it was included in the main repo. The @types (formerly DefinitelyTyped) are for third party typings

[nothingismagick]

@outofmemoryagain and @rstoenescu - is this still helpful or can it be closed because the work being done on the typedefs in core and this app-extension here:

https://github.com/quasarframework/app-extension-typescript