Fix return type of listeners in typescript def
Fix return type of listeners in typescript def

According to [1], `void` should be used instead of `any` for return types of callbacks whose value will be ignored.

[1] https://www.typescriptlang.org/docs/handbook/declaration-files/do-s-and-don-ts.html

Change-Id: I52ab02e18141e77bfe613b24f33b49395ce9de01

eclipsesource/tabris-js,eclipsesource/tabris-js,eclipsesource/tabris-js