Address TODO comments across the code base

[shamblett]

There are a a few TODO comments building up across the code base, see below, these need to be either fixed or removed if no longer needed.

Found 17 TODO items in 6 files

coap_link_format.dart (22, 6) // TODO(JKRhb): Revisit typing (63, 6) // TODO(JKRhb): This needs to be a value between 1 and 4294967295.

integer_option.dart (27, 8) // TODO(JKRhb): The handling of endianness should be revisited here. (46, 8) // TODO(JKRhb): The handling of endianness should be revisited here. (190, 4) // TODO(JKRhb): Is this really a class U option? (228, 4) // TODO(JKRhb): Is this really a class E option? (238, 4) // TODO(JKRhb): Is this really a class E option?

oscore_option.dart (8, 4) // TODO(JKRhb): This currently can only contain encoded values and does not (22, 6) // TODO(JKRhb): Maybe this can be done more elegantly

coap_client.dart (40, 4) // FIXME: The name MatchETags might be a bit misleading, c.f. https://datatracker.ietf.org/doc/html/rfc7252#section-5.10.8.2

coap_media_type.dart (336, 6) // TODO(JKRhb): Are there any uncovered cases?

coap_message.dart (107, 10) // TODO(JKRhb): Revisit conditions for rejection (238, 6) // TODO(JKRhb): Should rejections be included here as well? (430, 6) // TODO(JKRhb): Apply proper percent-encoding (469, 6) // TODO(JKRhb): Apply proper percent-encoding (512, 6) // TODO(JKRhb): Apply proper percent-encoding (560, 6) // TODO(JKRhb): Apply proper percent-encoding