Standardize Card to String conversion to use UTF-8 suit symbols

[pashadia]

This will allow the Cards to be parsed back from their .to_string() output.

[Nydauron]

I like the addition.

The one thing I didn't realize about Display is that it implicitly implements the trait ToString. So, there are two different string conversion methods, the other one being:

playing-cards/src/core/card.rs

Lines 333 to 337 in 51adfa4

	impl From<Card> for String {
	fn from(c: Card) -> Self {
	format!("{}{}", c.value.get_char(), c.suit.get_char())
	}
	}

which prints out an alpha character for the suit rather than a symbol. My intentions with Display were to provide a prettified way of displaying the cards while also giving another the option to convert the Card (unaware of ToString). Seeing that there doesn't seem to be a way to override the blanket implementation, I guess it is best to also change From<Card> to just use to_string() (same inconsistency issue applies to From<Suit> for char).

If those changes could be made, alongside adding some additional documentation to Suit::from_char() referencing the ability to parse symbols, I think the PR would be good to merge.

[pashadia]

I've made those changes, with the following exception:

same inconsistency issue applies to From<Suit> for char

That's incorrect. .to_string() returns a String not a char.

[Nydauron]

The inconsistency I was referring to was that suit.into::<char>() currently returns back an alpha character (e.g. 'h') while suit.to_string() returns a symbol string (e.g. "♥"). Ideally these should be the same character (the return types still being a char and a String respectively):

let suit = Suit::Heart;
assert_eq!(suit.into::<char>(), '♥');
assert_eq!(suit.to_string(), "♥");

[pashadia]

Ok, that's doable, but are you sure you want that?

I think that having some way in which the structs would return an alphanumeric char/string could be beneficial for testing and rapid prototyping purposes.