Update copy.sh for better WSL support

terminal/copy.sh

@@ -14,14 +14,29 @@ fail() {
     exit "${2:-1}"
 }
 
+wsl_copy() {
+  # This function is superior to Windows' copy.exe, since it does not mess up
+  # text encoding by asssuming BOM.
+  # https://github.com/microsoft/WSL/issues/10095#issuecomment-1602833117
+  INPUT="$(cat; echo x)"
+  declare -r INPUT="${INPUT%x}" # https://stackoverflow.com/a/32365596/893211
+# Note that the string terminator '@ must be on a separate line and must not
+# have leading whitespace:
+# https://devblogs.microsoft.com/scripting/powershell-for-programmers-here-strings-there-strings-everywhere-some-string-strings/
+powershell.exe -c "Set-Clipboard @'
+${INPUT}
+'@
+"
+}
+
 if [[ "$(uname -r)" =~ .*microsoft.* ]]; then
   declare -r IS_WSL=true
 else
   declare -r IS_WSL=false
 fi
 
 if [[ "${IS_WSL}" == "true" ]]; then
-  declare -r CLIPBOARD_CMD='/mnt/c/Windows/System32/clip.exe'
+  declare -r CLIPBOARD_CMD=wsl_copy
 else
   missing_dependencies=false
   declare -r dependencies=(