Create script to build installer .exe or .msi for Windows (runnable on windows 7 x64 and newer)

### Task Description

The aim of this task is to revisit creation of the Windows installable package (the Nullsoft installer is currenly used) of BGL Core. It's largely the same script and process as the Bitcoin Core installation script, with same dependencies and build process.
It uses VS2019 image to build the installation executable package.
https://github.com/wu-emma/bitgesell/blob/master/.appveyor.yml

You can create free account on AppVeyor.com at https://www.appveyor.com/

### Solution steps
- Ensure that windows build is working (including Qt wallet), this will require Visual Studio (download VS2019 Community Edition if you don't have one installed);
- There are dependencies installed using vcpkg, but the more complicated thing is Qt, which should be installed by hand (check existing AppVeyor script link https://github.com/sipsorcery/qt_win_binary/releases/download/v1.6/Qt5.9.8_x64_static_vs2019.zip);
- Fix dependencies or project settings (if needed) in build_msvc;
- Sign up to AppVeyor free tier;
- Fix AppVeyor script in .appveyor.yml

### Acceptance criteria
- AppVeyor has a free tier -- please sign up for it, project is public, so it is allowed;
- AppVeyor can automatically build Windows installable package for Windows x64 platform;
- Along with pull request (which probably would be rather short), provide sample of built setup executable and short notes of integrating/fetching built artifacts from AppVeyour build.

Start by reviewing .appveyor.yml and the build_msvc settings, then verify that the Windows build and Qt wallet build successfully with the stated VS2019, vcpkg, and Qt dependencies. Compare the process with the referenced Bitcoin Core installation script. Done means AppVeyor produces a Windows x64 installer and the pull request includes a sample setup executable and artifact integration notes.

Written by the indexing model from the issue text.