Fix stdin/stdout encoding on Windows. (#2425)

QTextStream uses the system default locale, but this breaks in
various situations: (1) It does not work on the native Windows shell
(cmd.exe, Powershell), since the default Windows locale is Windows-1252,
but the shell uses Windows-850. (2) It also breaks on *nix systems where
the locale is Latin1 or C, which is the case for most CI systems or
build servers.

We allow overriding the detected codec by setting the ENCODING_OVERRIDE
environment variable, but otherwise prefer Windows-850 on Windows and
UTF-8 on any other system, even if LANG is set to something else.

This resolves #2413

src/cli/keepassxc-cli.cpp

@@ -20,8 +20,8 @@
 #include <QCommandLineParser>
 #include <QCoreApplication>
 #include <QStringList>
-#include <QTextStream>
 
+#include "cli/TextStream.h"
 #include <cli/Command.h>
 
 #include "config-keepassx.h"
@@ -46,7 +46,7 @@ int main(int argc, char** argv)
     Bootstrap::bootstrapApplication();
 #endif
 
-    QTextStream out(stdout);
+    TextStream out(stdout);
     QStringList arguments;
     for (int i = 0; i < argc; ++i) {
         arguments << QString(argv[i]);