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/Applications/SystemMonitor/ProcessModel.h

@@ -7,7 +7,7 @@
 
 #pragma once
 
-#include <AK/DeprecatedString.h>
+#include <AK/ByteString.h>
 #include <AK/HashMap.h>
 #include <AK/Vector.h>
 #include <LibGUI/Icon.h>
@@ -110,14 +110,14 @@ private:
         u64 time_user { 0 };
         u64 time_kernel { 0 };
         bool kernel { false };
-        DeprecatedString executable { "" };
-        DeprecatedString name { "" };
+        ByteString executable { "" };
+        ByteString name { "" };
         Variant<String, EmptyCommand> command { EmptyCommand::NotInitialized };
         uid_t uid { 0 };
-        DeprecatedString state { "" };
-        DeprecatedString user { "" };
-        DeprecatedString pledge { "" };
-        DeprecatedString veil { "" };
+        ByteString state { "" };
+        ByteString user { "" };
+        ByteString pledge { "" };
+        ByteString veil { "" };
         u32 cpu { 0 };
         u32 priority { 0 };
         size_t amount_virtual { 0 };