Improve formatting of single-constructor types and records

[janmasrovira]

• Closes Don't add a pipe when there is only one constructor #2331.

The rules implemented in this pr are as follows.

1. If a type definition has only one constructor, no pipe is added. The constructor is printed in the same line if it fits.
2. If a constructor is a record with a single field, the field is printed in the same line if it fits. If the constructor has multiple fields, they are printed aligned and indented after a line break.

Examples:

type T := constructT : T;

type T-wrapper := mkWrapper {unwrap : T};

type EnumRecord :=
  | --- doc for C1
    C1 {
      c1a : T;
      c1b : T
    }
  | C2 {
      c2a : T;
      c2b : T
    };