Add a new macro argument for enums to change a flag value

[zhiburt]

#[derive(Tabled)]
enum Domain {
    Security,
    Embedded,
    Frontend,
    Unknown,
}
     
let data = vec![
    Domain::Embedded,
    Domain::Security,
    Domain::Frontend,
    Domain::Unknown,
];
  
assert_eq!(
    table,
    concat!(
        " Security | Embedded | Frontend | Unknown \n",
        "----------+----------+----------+---------\n",
        "          |    +     |          |         \n",
        "    +     |          |          |         \n",
        "          |          |    +     |         \n",
        "          |          |          |    +    "
    )
);

The idea is to change this +.
I do not know what the perfect name for it.

But we surely could support with_display which is currently not suported for enum as I understand.

[zhiburt]

By the way I guess we could add a logic switch of how to represent enum.

As we could use just its variant name instead of this verse + logic.