Added domain separation in keygen and new KATs.
The KATs were sourced from post-quantum-cryptography/KAT#15.

Added domain separation in keygen and new KATs.
The KATs were sourced from post-quantum-cryptography/KAT#15.

In this PR we made a small change that transitions the ML-KEM
implementation from the Initial Public Draft (IPD) to the final ML-KEM
as defined in FIPS 203:
https://nvlpubs.nist.gov/nistpubs/FIPS/NIST.FIPS.203.pdf.
The only change needed was the domain separation in key generation.
This required updated KATs as well. The new KATs were obtained from:
post-quantum-cryptography/KAT#15,
and converted to the form AWS-LC expects.

In as subsequent PR we'll rename all functions/folders/identifiers
to drop the "ipd" suffix.

p.s. Python script used for KATs conversion:
```
import sys

if len(sys.argv) != 2:
    print("Usage: python convert.py <filename>")
    sys.exit(1)
filename = sys.argv[1]

# PARSE THE INPUT FILE
all_groups = []
try:
    with open(filename, 'r') as file:
        group = {}
        for line in file:
            key = line.strip().split(" ")[0]
            value = line.strip().split(" ")[2]
            if key == "count":
                if (len(group) != 0):
                    all_groups.append(group)
                group = {}
            group[key] = value
except FileNotFoundError:
    print(f"Error: The file '{filename}' was not found.")

try:
    with open(filename + "_out.txt", 'w') as file:
        for group in all_groups:
            file.write("\n")
            file.write("count = " + group["count"] + "\n")
            file.write("keypair_coins = " + group["d"] + group["z"] + "\n")
            file.write("pk = " + group["pk"] + "\n")
            file.write("sk = " + group["sk"] + "\n")
            file.write("encap_coins = " + group["msg"] + "\n")
            file.write("ct = " + group["ct"] + "\n")
            file.write("ss = " + group["ss"] + "\n")

except FileNotFoundError:
    print(f"Error: The file '{filename}' was not found.")
```