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/LibJS/Module.h

@@ -117,7 +117,7 @@ public:
     virtual PromiseCapability& load_requested_modules(GCPtr<GraphLoadingState::HostDefined>) = 0;
 
 protected:
-    Module(Realm&, DeprecatedString filename, Script::HostDefined* host_defined = nullptr);
+    Module(Realm&, ByteString filename, Script::HostDefined* host_defined = nullptr);
 
     virtual void visit_edges(Cell::Visitor&) override;
 
@@ -140,7 +140,7 @@ private:
     Script::HostDefined* m_host_defined { nullptr }; // [[HostDefined]]
 
     // Needed for potential lookups of modules.
-    DeprecatedString m_filename;
+    ByteString m_filename;
 };
 
 class CyclicModule;