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/LibVT/Attribute.h

@@ -13,7 +13,7 @@
 #include <LibVT/XtermColors.h>
 
 #ifndef KERNEL
-#    include <AK/DeprecatedString.h>
+#    include <AK/ByteString.h>
 #endif
 
 namespace VT {
@@ -37,8 +37,8 @@ struct Attribute {
     Color background_color { default_background_color };
 
 #ifndef KERNEL
-    DeprecatedString href;
-    Optional<DeprecatedString> href_id;
+    ByteString href;
+    Optional<ByteString> href_id;
 #endif
 
     enum class Flags : u8 {