`ReplaceConstant` may require adding explicit type cast

This is a corner case and also rather unlikely to be seen in the wild, but when a constant is replaced with null the value may require an explicit type cast. See this test case where a type cast is required due to method overloads:

    @Test
    void addsExplicitCastWhenReplacingWithNullAndOverloadRequiresIt() {
        assertThrows(AssertionError.class, () ->
          rewriteRun(
            spec -> spec.recipe(new ReplaceConstant("com.abc.A", "VAR", "null")),
            java(
                """
                package com.abc;
                class A {
                    public static final String VAR = "default";
                    private String m1() {
                        return m2(VAR);
                    }
                    private String m2(String s) {
                        return s;
                    }
                    private String m2(Integer i) {
                        return i.toString();
                    }
                }
                """,
              """
                package com.abc;
                class A {
                    public static final String VAR = "default";
                    private String m1() {
                        return m2((String) null);
                    }
                    private String m2(String s) {
                        return s;
                    }
                    private String m2(Integer i) {
                        return i.toString();
                    }
                }
                """
            )
          ));
    }

Start at the ReplaceConstant recipe and use the supplied addsExplicitCastWhenReplacingWithNullAndOverloadRequiresIt test case as the entry point. Reproduce the overload scenario, then verify that replacing the constant with null produces an explicit String cast and that the test passes.