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/Utilities/ping.cpp

@@ -30,7 +30,7 @@ static Optional<size_t> count;
 static uint32_t total_ms;
 static int min_ms;
 static int max_ms;
-static DeprecatedString host;
+static ByteString host;
 static int payload_size = -1;
 static bool quiet = false;
 static Optional<size_t> ttl;