AppVeyor: install and include OpenSSL

Qt5 does not include OpenSSL libraries it was build against. See https://forum.qt.io/topic/95700/qsslsocket-tls-initialization-failed/18

As a result we have to make sure a compatible libssl.dll and libcrypto.dll is included in PATH when the software is loaded. It seems not to be detected by our Python dependency script. So, I added it manually like the JACK library.

Important: when upgrading/downgrading the Qt version a different version of OpenSSL might be required. One has to manually check the version it was build against https://wiki.qt.io/Qt_5.15_Tools_and_Versions#windows_10_x86_64_7.

But this can also be abstracted by a unit test as soon as the GUI can also be covered (I think we have to build a dedicated library as in #1329 first).

.appveyor.yml

@@ -19,6 +19,9 @@ environment:
       CMAKE_FLAGS: "-DWANT_DEBUG:BOOL=OFF -DWIN64:BOOL=ON"
       appveyor_build_worker_image: Visual Studio 2019
       LIBJACK: libjack64.dll
+      OPENSSL_DIR: OpenSSL-Win64
+      LIBSSL: libssl-1_1-x64.dll
+      LIBCRYPTO: libcrypto-1_1-x64.dll
       CHOCO_ARCH:
       PROGRAM_FILES: "Program Files"
 
@@ -30,6 +33,9 @@ environment:
       CMAKE_FLAGS: "-DWANT_DEBUG:BOOL=OFF -DWIN64:BOOL=OFF"
       appveyor_build_worker_image: Visual Studio 2019
       LIBJACK: libjack.dll
+      OPENSSL_DIR: OpenSSL-Win32
+      LIBSSL: libssl-1_1.dll
+      LIBCRYPTO: libcrypto-1_1.dll
       CHOCO_ARCH:  --x86
       PROGRAM_FILES: "Program Files (x86)"
 
@@ -123,6 +129,10 @@ for:
           dir "c:\%PROGRAM_FILES%\JACK2"
           dir "c:\%PROGRAM_FILES%\JACK2\lib"
 
+          choco install %CHOCO_ARCH% -y openssl --version=1.1.1.1300
+
+          dir "c:\%PROGRAM_FILES%\%OPENSSL_DIR%"
+
           REM *** Install dependencies ***
           c:\msys64\usr\bin\pacman --noconfirm -S -q %MSYS_REPO%-libarchive
           c:\msys64\usr\bin\pacman --noconfirm -S -q %MSYS_REPO%-libsndfile
@@ -175,7 +185,9 @@ for:
           REM copy_third_party_libs.py thinks it's a system lib and
           REM won't copy it.
           copy c:\Windows\%LIBJACK% %APPVEYOR_BUILD_FOLDER%\build\windows\extralibs
-
+          copy c:\%PROGRAM_FILES%\%OPENSSL_DIR%\%LIBSSL% %APPVEYOR_BUILD_FOLDER%\build\windows\extralibs
+          copy c:\%PROGRAM_FILES%\%OPENSSL_DIR%\%LIBCRYPTO% %APPVEYOR_BUILD_FOLDER%\build\windows\extralibs
+          
           REM *** Build installer ***
           cpack -G NSIS -v