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/HTML/Canvas/CanvasState.h

@@ -58,7 +58,7 @@ public:
         {
             return m_fill_or_stroke_style.visit(
                 [&](Gfx::Color color) -> JsFillOrStrokeStyle {
-                    return MUST(String::from_deprecated_string(color.to_deprecated_string()));
+                    return MUST(String::from_byte_string(color.to_byte_string()));
                 },
                 [&](auto handle) -> JsFillOrStrokeStyle {
                     return handle;