Allow using `..` on tuples in function expressions

[SheepTester]

See https://discord.com/channels/710932856251351111/710936824121655396/878023177572347936

let printNums = [a:int b:int c:int] -> cmd[()] {
  assert value a == 1
  assert value b == 2
  assert value c == 3
}

let tuple = (1, 2)

let pub main = printNums (..tuple, 3)

Not in this issue:

• Using .. on tuples within tuple expressions