The record layer splits application data into chunks of at most 2^14
octets. When record protection is engaged in TLS 1.3, the application
data is serialized into a TLSInnerPlaintext which has an additional byte
for the content type, resulting in a maximum length of 2^14+1.
Fixes LargeMessage, TLS13-AEAD-CHACHA20-POLY1305-LargeRecord,
TLS13-AEAD-AES128-GCM-SHA256-LargeRecord and
TLS13-AEAD-AES256-GCM-SHA384-LargeRecord bogo tests.
Fixes: https://github.com/cloudflare/tls-tris/issues/46