remove windows support

The way drkonqi works makes little to no sense on windows because users get stripped binaries and there is no way to download debug symbols, it also makes little to no sense to download debug symbols on windows in general. We are provider of the binaries so given a minidump we could always retrace them on our end. These days we can get crash reports through the windows store which means we don't need extra UIs on top of what windows already offers.

This lightens our code base, removes a whole bunch of unused features (to my knowledge no body actually uses drkonqi on windows) and by extension means we don't have parts of plasma target windows on a CI-level causing unnecessary headaches.

(All of this technically also applies to OSX - a discussion we should also have I guess)

discussed @ https://markmail.org/message/hoce74pew3cxopck