feat: Add refineFurther methods to chain refinements

[Iltotore]

Add refineFurther (and monadic variants) to enable fine-grained refinement of the same value. Here is the motivating example in docs:

type Username = DescribedAs[Alphanumeric, "Username should be alphanumeric"]
type Password = DescribedAs[
  Alphanumeric & MinLength[5] & Exists[Letter] & Exists[Digit],
  "Password should have at least 5 characters, be alphanumeric and contain at least one letter and one digit"
]

case class User(name: String :| Username, password: String :| Password)

def createUser(name: String, password: String): Either[String, User] =
  for
    validName     <- name.refineEither[Username]
    alphanumeric  <- password.refineEither[Alphanumeric]
    minLength     <- alphanumeric.refineFurtherEither[MinLength[5]]
    hasLetter     <- minLength.refineFurtherEither[Exists[Letter]]
    validPassword <- hasLetter.refineFurtherEither[Exists[Digit]]
  yield
    User(validName, validPassword)

createUser("Iltotore", "abc123") //Right(User("Iltotore", "abc123"))
createUser("Iltotore", "abc1") //Left("Should have a minimum length of 5")
createUser("Iltotore", "abcde") //Left("At least one element: (Should be a digit)")
createUser("Iltotore", "abc123  ") //Left("Should be alphanumeric")

Closes #106

@GiGurra did I miss something or does it fulfill your need?

[GiGurra]

Thanks!