best AST representation for literals

[avh4]

Part of #194.

should literals be represented as 🅰️

...
    | StringLiteral { value : String, ... }
    | FloatLiteral { value : Float, ... }
    | IntLiteral { value: Int, ... }
    | CharLiteral { value: String, ... }

or as 🅱️

 ...
    | Literal { value : LiteralValue }

LiteralValue =
    | StringValue { value : String, ... }
    | IntValue { value : Int, ... }
    ...

In favor of 🅰️:

• 🅰️ 1️⃣ less nesting

In favor of 🅱️:

• 🅱️ 1️⃣ fewer things to destructure for clients that don't care about the values of literals.

[avh4]

My inclination at the moment is that point 🅱️ 1️⃣ is stronger than point 🅰️ 1️⃣