fix: handle utf8 in input properly

[Nerixyz]

The input didn't handle UTF-16 to UTF-8 conversion properly (why is this converted in the first place?) - it truncated the bytes. For the ASCII subset of Unicode, this works fine. For other Unicode characters (e.g. emoji), this is invalid. Since we're on Windows, we can use WideCharToMultiByte.

Semi-related changes:

Console Example

• Added --input
• Turned the executable into a true console app instead of a GUI app (subsystem console)
• Added an exit upon receiving a reply
• Set the console code page to UTF-8 (required for UTF-8 to be printed correctly)

Qt Example

• Added an "Add Input" checkbox
• Note: this example doesn't require the console code page to be set to UTF-8 (Qt probably does that already)

I tested this with the input hello 😂😂😂😂 and verified that it prints correctly in the terminal (I used VS Code's terminal and MS terminal). This might not display correctly in CMD, so Microsoft's new Terminal has to be used. When testing the Qt version, set $Env:QT_WIN_DEBUG_CONSOLE="attach" (powershell), so the app prints to the parent console.