Large Record Sizes for TLS and DTLS with Reduced Overhead

TLS 1.3 records limit the inner plaintext (TLSInnerPlaintext) size to 2^14 + 1 bytes, which includes one byte for the content type. DTLS 1.3 uses the same plaintext size limit. This document defines a TLS extension that allows endpoints to advertise larger per-direction maximum inner plaintext sizes, up to 2^30 - 256 bytes, while reducing overhead in TLS 1.3 and DTLS 1.3 record headers.