Implement Remaining Cases of Expr in API Gateway Spec

[vigoo]

Implement Remaining Cases of Expr in API Gateway Spec

[afsalthaj]

This is already done.

The cases implemented are:

#[derive(Debug, Clone, PartialEq, Encode, Decode)]
pub enum Expr {
    Request(),
    WorkerResponse(),
    SelectField(Box<Expr>, String),
    SelectIndex(Box<Expr>, usize),
    Sequence(Vec<Expr>),
    Record(Vec<(String, Box<Expr>)>),
    Literal(String),
    Number(InnerNumber),
    Variable(String),
    Boolean(bool),
    PathVar(String),
    Concat(Vec<Expr>),
    Not(Box<Expr>),
    GreaterThan(Box<Expr>, Box<Expr>),
    GreaterThanOrEqualTo(Box<Expr>, Box<Expr>),
    LessThanOrEqualTo(Box<Expr>, Box<Expr>),
    EqualTo(Box<Expr>, Box<Expr>),
    LessThan(Box<Expr>, Box<Expr>),
    Cond(Box<Expr>, Box<Expr>, Box<Expr>),
    PatternMatch(Box<Expr>, Vec<ConstructorPatternExpr>),
    Constructor0(ConstructorPattern), // Can exist standalone from pattern match
}