Decouple the dropper and the WormConfiguration

[mssalvatore]

The WormConfiguration contains settings used only by the dropper. More importantly, these "configuration" options aren't configurable anywhere.

Decouple the dropper and the worm configuration by making the "dropper config" options constants on the dropper class.

Tasks

• Move dropper config option from monkey/infection_monkey/config.py to consts in related modules. @ilija-lazoroski
• Extract "dropper_target_path_linux" and "dropper_target_path_win_64" away from the configuration into dropper related modules. (0d) @ilija-lazoroski
• Create a documentation page explaining how agent propagation works and what are the paths the agents are uploaded to. (0d) - @shreyamalviya