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/LibWeb/WebGL/WebGLContextAttributes.cpp

@@ -99,7 +99,7 @@ JS::ThrowCompletionOr<WebGLContextAttributes> convert_value_to_context_attribute
     WebGLPowerPreference power_preference_value { WebGLPowerPreference::Default };
 
     if (!power_preference.is_undefined()) {
-        auto power_preference_string = TRY(power_preference.to_deprecated_string(vm));
+        auto power_preference_string = TRY(power_preference.to_byte_string(vm));
 
         if (power_preference_string == "high-performance"sv)
             power_preference_value = WebGLPowerPreference::HighPerformance;