Everywhere: Rename {Deprecated => Byte}String

This commit un-deprecates DeprecatedString, and repurposes it as a byte
string.
As the null state has already been removed, there are no other
particularly hairy blockers in repurposing this type as a byte string
(what it _really_ is).

This commit is auto-generated:
  $ xs=$(ack -l \bDeprecatedString\b\|deprecated_string AK Userland \
    Meta Ports Ladybird Tests Kernel)
  $ perl -pie 's/\bDeprecatedString\b/ByteString/g;
    s/deprecated_string/byte_string/g' $xs
  $ clang-format --style=file -i \
    $(git diff --name-only | grep \.cpp\|\.h)
  $ gn format $(git ls-files '*.gn' '*.gni')

Userland/Libraries/LibDNS/Packet.cpp

@@ -150,7 +150,7 @@ ErrorOr<Packet> Packet::from_raw_packet(ReadonlyBytes bytes)
         if (record.data_length() > bytes.size() - offset)
             return Error::from_string_literal("Unexpected EOF when parsing DNS packet");
 
-        DeprecatedString data;
+        ByteString data;
 
         switch ((RecordType)record.type()) {
         case RecordType::PTR: {