MEDIUM: quic: implement CHACHA20_POLY1305 for AWS-LC

MEDIUM: quic: implement CHACHA20_POLY1305 for AWS-LC

With AWS-LC, the aead part is covered by the EVP_AEAD API which
provides the correct EVP_aead_chacha20_poly1305(), however for header
protection it does not provides an EVP_CIPHER for chacha20.

This patch implements exceptions in the header protection code and use
EVP_CIPHER_CHACHA20 and EVP_CIPHER_CTX_CHACHA20 placeholders so we can
use the CRYPTO_chacha_20() primitive manually instead of the EVP_CIPHER
API.

This requires to check if we are using EVP_CIPHER_CTX_CHACHA20 when
doing EVP_CIPHER_CTX_free().