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/LibCrypto/PK/PK.h

@@ -9,7 +9,7 @@
 #include <AK/ByteBuffer.h>
 
 #ifndef KERNEL
-#    include <AK/DeprecatedString.h>
+#    include <AK/ByteString.h>
 #endif
 
 namespace Crypto::PK {
@@ -36,7 +36,7 @@ public:
     virtual void verify(ReadonlyBytes in, Bytes& out) = 0;
 
 #ifndef KERNEL
-    virtual DeprecatedString class_name() const = 0;
+    virtual ByteString class_name() const = 0;
 #endif
 
     virtual size_t output_size() const = 0;