Add wildcard test for const_if_match

Closes #66758

Author: jyn514

src/test/ui/consts/control-flow/single-arm-match-wild.rs

@@ -0,0 +1,19 @@
+// check-pass
+
+#![feature(const_if_match)]
+
+enum E {
+    A,
+    B,
+    C
+}
+
+const fn f(e: E) -> usize {
+    match e {
+        _ => 0
+    }
+}
+
+fn main() {
+    assert_eq!(f(E::A), 0);
+}