This PR adds support for records in pattern matching and an update to pattern matching itself.

Fields can be matched with the same syntax as records:

type User {
  name: String,
  age: Number
}

case { name: "John", age: 42 } {
  { name: name, age: 42 } => name
  => "Unkown"
}

The other change is that patterns are now limited to the following ones:

• Type: Maybe(...)
• Record: {...}
• Tuple: {a, b}
• Array: [...]
• Variable: a
• String literal (without interpolation): "a"
• Number literal: 0.1
• Bool literal: true

It's needed, so exhaustiveness checking works reliably, for example:

type SomeType {
  A
  B
}

fun test(value: SomeType, otherValue: SomeType) {
  case value {
    // if otherValue here is the variable above
    otherValue => "X"
    SomeType.A => "A"
    SomeType.B => "B"
  }
}

In the example above, we can't be sure which branch is redundant, since we don't know the value of otherValue at compile time.

I'll try to do explore how to enable this in the future. Elixir has it, but they don't support exhaustiveness, Gleam, Rust and Elm don't allow this, not sure if other languages do. If anyone has research on it, let me know :)