use correct error for unused bind match, suppress with underscore

modules/gdscript/tests/scripts/parser/features/match_bind_unused.gd

@@ -0,0 +1,13 @@
+# https://github.com/godotengine/godot/pull/61666
+
+func test():
+	var dict := {"key": "value"}
+	match dict:
+		{"key": var value}:
+			print(value) # used, no warning
+	match dict:
+		{"key": var value}:
+			pass # unused, warning
+	match dict:
+		{"key": var _value}:
+			pass # unused, suppressed warning from underscore

modules/gdscript/tests/scripts/parser/features/match_bind_unused.out

@@ -0,0 +1,6 @@
+GDTEST_OK
+>> WARNING
+>> Line: 9
+>> UNUSED_VARIABLE
+>> The local variable 'value' is declared but never used in the block. If this is intended, prefix it with an underscore: '_value'
+value