frontend: Add utf-8 active code page manifest

Declaring Utf-8 as active code page in manifest makes Win32 API use utf-8 instead of ANSI codepages when using the "A" versions of functions.

Manifest declaration also encodes command line arguments as utf8. This allows for example --profile <name> to load profiles with special characters.

Author: Dankirk

frontend/cmake/windows/obs.manifest

@@ -11,6 +11,11 @@
             </requestedPrivileges>
         </security>
     </trustInfo>
+    <application>
+	<windowsSettings>
+	    <activeCodePage xmlns="http://schemas.microsoft.com/SMI/2019/WindowsSettings">UTF-8</activeCodePage>
+        </windowsSettings>
+    </application>
     <compatibility xmlns="urn:schemas-microsoft-com:compatibility.v1">
         <application>
             <!-- Windows 10 and Windows 11 -->

libobs/obs.h

@@ -382,8 +382,11 @@ EXPORT const char *obs_get_version_string(void);
  * and safely copies argv/argc from main(). Subsequent calls do nothing.
  *
  * @param  argc  The count of command line arguments, from main()
- * @param  argv  An array of command line arguments, copied from main() and ends
+ * @param  argv  An array of command line arguments in UTF-8, copied from main() and ends
  *               with NULL.
+ * 
+ *		 On Windows this requires that active code page is UTF-8.
+ *		 For example as a declaration in obs.manifest.
  */
 EXPORT void obs_set_cmdline_args(int argc, const char *const *argv);