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/DevTools/HackStudio/ToDoEntriesWidget.cpp

@@ -63,9 +63,9 @@ public:
             case Column::Text:
                 return match.content;
             case Column::Line:
-                return DeprecatedString::formatted("{}", match.line + 1);
+                return ByteString::formatted("{}", match.line + 1);
             case Column::Column:
-                return DeprecatedString::formatted("{}", match.column);
+                return ByteString::formatted("{}", match.column);
             }
         }
         return {};