Add Windows support

[r4sas]

What's Changed

• Updated CMake configuration to make possible to build application on Windows
• Added preprocessor definitions to use MVC-related code when building on Windows
• Added precompiled mimetic library (temporary? - we need to add it to MSYS2)

Checklist:

• My code follows the style guidelines of this project
• I have performed a self-review of my code
• My changes generate no new warnings
• Changes do not affect Core Features [e.g operation with DHT, mail sending, etc.]

TODO:

• Write Windows services manager callbacks handler
• Add resources file
• Add minimalistic tray UI

[r4sas]

[r4sas]

TODO:

• Write Windows services manager callbacks handler
• Add resources file
• Add minimalistic tray UI - TODO

[r4sas]

@polistern let's merge it without WinAPI tray icon for now.