Add quote patterns runtime

[nicolasstucki]

This PR adds:

• runtime logic for pattern matching on '{ ... }
• Literal pattern to match a literal expression and extract its value

With this we will be able to write and run pattern matches like

def optimize(expr: Expr[Int]): Expr[Int] = expr match {
  case '{ 0 + $y } => optimize(y)
  case '{ ${Literal(a)} + ${Literal(b)} } => (a + b).toExpr
  case '{ ${x} + ${y @ Literal(_)} } => optimize('{ $y + $x })
  ...
  case expr => expr
}

[nicolasstucki]

Rebased