draft-ietf-httpbis-encryption-encoding-08, Relaxing UTF-8 requirement for `keyid`

Hi,

In https://tools.ietf.org/html/draft-ietf-httpbis-encryption-encoding-08#section-2.1 <https://tools.ietf.org/html/draft-ietf-httpbis-encryption-encoding-08#section-2.1>, the `keyid` parameter is defined to be a UTF-8 encoded string. However, https://webpush-wg.github.io/webpush-encryption <https://webpush-wg.github.io/webpush-encryption> uses the `keyid` to encode the sender's ephemeral DH public key.

Given that this field can be used to carry any kind of keying info, I'm wondering if we might relax the UTF-8 requirement.

Cheers,
- kit