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/LibDebug/Dwarf/LineProgram.cpp

@@ -81,7 +81,7 @@ ErrorOr<void> LineProgram::parse_path_entries(Function<void(PathEntry& entry)> c
             StringBuilder builder;
             while (auto c = TRY(m_stream.read_value<char>()))
                 TRY(builder.try_append(c));
-            auto path = builder.to_deprecated_string();
+            auto path = builder.to_byte_string();
             if (path.length() == 0)
                 break;
             dbgln_if(DWARF_DEBUG, "path: {}", path);