fix(single-instance): forward non-Unicode arguments and cwd (#3644)

* Update windows.rs

* Create single-instance-non-unicode-args.md

* fix on linux and windows too

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Co-authored-by: Lucas Nogueira <lucas@tauri.app>

.changes/single-instance-non-unicode-args.md

@@ -0,0 +1,5 @@
+---
+"single-instance": patch
+---
+
+A second instance no longer panics when a command-line argument is not valid Unicode: such an argument is forwarded with its invalid parts replaced by U+FFFD. A working directory that is not valid Unicode is now forwarded the same way instead of as an empty string.