[Legal] Qt 5 binary installer does not display license page

The Qt 4.x installer wizard displays the LGPL and asks the user to agree to the terms of that license. The Qt 5 installer appears to be missing this page.

Qt Project Legal have requested that this page be added to the new installer, on the basis that in a binary package the user doesn't generally see the license headers in source files, so the license page in the installer is the primary way that we communicate the licensing information to users.