[feature] export Keyword

[Vurv78]

Is your feature request related to a problem? Please describe.
Need to be able to export created variables and functions from extensions to user chips,

Describe the solution you'd like
You could export variables in order to pass them to user chips

export const foo = 55;

Describe alternatives you've considered
Taking them from the scope, although this would be way less explicit and could lead to variable collisions

Additional context
This is needed mostly for extensions right now, since modules / imports are not a thing
This should also replace the existing auto-exporting behavior of declare, so instead of typing

declare var CLIENT: boolean;

you'd now put

export declare var CLIENT: boolean;

as you'd see in regular typescript.