GnuTLS with kernel TLS, and forgectrl.tls-records

The gnutls bbappend builds GnuTLS with --enable-ktls and installs
/etc/gnutls/config with ktls = true, so after the handshake the kernel
seals and opens forgectrl's HTTPS records (the kernel side is
meta-openglow's CONFIG_TLS and patch 0016). It also backports GnuTLS
dc016daf: 3.8.4 hands the kernel the record sequence number where a TLS
1.2 ChaCha20-Poly1305 connection's IV belongs, so every such connection
failed the kernel's first decryption. forgectrl is the only program on
the image that links GnuTLS.

forgectrl.tls-records, in its own module (suite/tlsrec.py), reads the
result from the outside with openssl s_client on loopback: a desktop
offer (AES-GCM first) gets ChaCha20-Poly1305 over TLS 1.3 and 1.2 and the
kernel takes both directions' keys; an AES-128-GCM-only offer, three
times over each protocol, gets it, the kernel takes its keys, and the
CAAM's job-ring interrupt counts the records; a TLS 1.2 CBC-only offer
connects and stays in GnuTLS (the control for the kernel's counters);
every copy of the panel page equals the plain-HTTP copy byte for byte,
with no decrypt error; the kernel's drivers are
rfc7539(chacha20-neon,poly1305-neon) and ctr-aes-caam with ghash-ce.

Proof: on the image before these fixes the test failed on both bugs it
names (the TLS 1.2 ChaCha20 page arrived empty with a decrypt error; the
AES-GCM pages arrived damaged); on image 20260927224418 it passes. The
unit suite (500 tests) and the coverage lint (0 uncovered paths) pass on
the host.

meta-forgefirm/conf/distro/forgefirm.conf

@@ -38,6 +38,8 @@ hostname:pn-base-files = "forgefirm"
 #                code without poky's CVE patches
 #   no tpm, fips, dane, and no certificate compression (brotli, zlib,
 #   zstd), none of which the panel uses
+# Kernel TLS is built in and turned on by the gnutls bbappend
+# (recipes-support/gnutls), which also installs /etc/gnutls/config.
 PACKAGECONFIG:pn-gnutls = "libtasn1"
 
 # opengl stays: forgectrl's camera demosaic runs as GLES2 fragment