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/LibJS/Bytecode/BasicBlock.cpp

@@ -46,7 +46,7 @@ void BasicBlock::dump(Bytecode::Executable const& executable) const
     }
     warnln(":");
     while (!it.at_end()) {
-        warnln("[{:4x}] {}", it.offset(), (*it).to_deprecated_string(executable));
+        warnln("[{:4x}] {}", it.offset(), (*it).to_byte_string(executable));
         ++it;
     }
 }