fix: validate that parameter names are unique (#7882)

coderd/util/strings/strings.go

@@ -0,0 +1,19 @@
+package strings
+
+import (
+	"fmt"
+	"strings"
+)
+
+// JoinWithConjunction joins a slice of strings with commas except for the last
+// two which are joined with "and".
+func JoinWithConjunction(s []string) string {
+	last := len(s) - 1
+	if last == 0 {
+		return s[last]
+	}
+	return fmt.Sprintf("%s and %s",
+		strings.Join(s[:last], ", "),
+		s[last],
+	)
+}