Add win installer icon

[teon]

[wojcik91]

The icons we used to have were a part of the workaround we were using to sidestep our inability to build a proper MSI. They cannot be trivially restored.

@Va1ter Please provide following images for the windows installer:

1. Side banner (for first and last screen)

Must be 493px × 312px as specified here

2. Top banner (for remaining screens)

Must be 493px × 58px as specified here