`Compact` should verify correct quantity of `.` separated segments

[Erik1000]

In the FromStr implementation:

jose/src/format/compact.rs

Lines 105 to 116 in 15abbd4

	impl FromStr for Compact {
	type Err = NoBase64UrlString;
	/// Verifies if every part of the string is valid base64url format
	fn from_str(s: &str) -> Result<Self, Self::Err> {
	let parts = s
	.split('.')
	.map(Base64UrlString::from_str)
	.collect::<Result<Vec<_>, _>>()?;
	Ok(Self { parts })
	}
	}

We do not check if the quantity matches. For JWS it would be 3 segments, for JWE 5. I think it would be smart to check the correct length as well and not only in the decode operation.

jose/src/jws.rs

Lines 420 to 429 in 15abbd4

	impl<C, T: FromRawPayload<Context = C>> DecodeFormatWithContext<Compact, C>
	for JsonWebSignature<Compact, T>
	{
	type Decoded<D> = Unverified<D>;
	type Error = ParseCompactError<T::Error>;
	fn decode_with_context(input: Compact, context: &C) -> Result<Unverified<Self>, Self::Error> {
	if input.len() != 3 {
	return Err(ParseCompactError::InvalidLength);
	}

[Erik1000]

Then we can also replace Vec with an array of either 3 or 5 elements