This patch adds support for Hybrid Public Key Encryption (draft-irtf-cfrg-hpke-05).
Because the draft number (and the eventual RFC number) is an input to the key schedule, future updates will *not* be backwards compatible in terms of key material or encryption/decryption. For this reason, a default compilation will produce stubs that simply return an "Invalid Algorithm" error. To opt into using the HPKE functionality , compile with `NSS_ENABLE_DRAFT_HPKE` defined. Once finalized, this flag will not be required to access the functions.
Lastly, the `DeriveKeyPair` API is not implemented as it adds complextiy around PKCS #11 and is unnecessary for ECH.
Differential Revision: https://phabricator.services.mozilla.com/D73947
extra : moz-landing-system : lando