fix(ber): Explicit errors when decoding optional any, proper TLV extraction in sequence

[Nicceboy]

• When decoding optional values in BER, does not hide errors anymore and presence status is based on peeking the next tag
• When Any type field is in Sequence, the outermost TLV defined by explicit tag is extracted away
• When decoding Any outside of Sequence/Set context, TLV pattern is verified but data is just copied as it is. It is up to caller to decode it further with correct type/tag.

[Nicceboy]

I think there is "a bug" that was hidden by the .ok() mapping.

In

rasn/standards/pkix/tests/fuzz.rs

Lines 35 to 36 in 6204851

	let encoded = rasn::cer::encode(&value).unwrap();
	assert_eq!(value, rasn::cer::decode(&encoded).unwrap());

CER attempts to decode following bytes

30 80 06 01 00 00 00

as

rasn/standards/pkix/src/lib.rs

Lines 410 to 415 in 6204851

	pub struct AlgorithmIdentifier {
	/// The identifier for the algorithm.
	pub algorithm: ObjectIdentifier,
	/// Parameters for the algorithm, if any.
	pub parameters: Option<Any>,
	}

It does not correctly detect the ending EOC, rather it tried to parse it as tag but failed. It was mapped to None previously.

[Nicceboy]

Can be reviewed and fixes #488.