Assorted cleanups

- fix naming convention for `workingDirectory`
- use type alias for `EvalFiles` everywhere
- move `ponderMode` into `LimitsType`
- move limits parsing into standalone static function

closes https://github.com/official-stockfish/Stockfish/pull/5098

No functional change

src/nnue/evaluate_nnue.cpp

@@ -30,7 +30,6 @@
 #include <sstream>
 #include <string_view>
 #include <type_traits>
-#include <unordered_map>
 
 #include "../evaluate.h"
 #include "../misc.h"
@@ -452,9 +451,9 @@ bool save_eval(std::ostream&      stream,
 }
 
 // Save eval, to a file given by its name
-bool save_eval(const std::optional<std::string>&                              filename,
-               NetSize                                                        netSize,
-               const std::unordered_map<Eval::NNUE::NetSize, Eval::EvalFile>& evalFiles) {
+bool save_eval(const std::optional<std::string>& filename,
+               NetSize                           netSize,
+               const EvalFiles&                  evalFiles) {
 
     std::string actualFilename;
     std::string msg;

src/nnue/evaluate_nnue.h

@@ -26,8 +26,8 @@
 #include <memory>
 #include <optional>
 #include <string>
-#include <unordered_map>
 
+#include "../evaluate.h"
 #include "../misc.h"
 #include "../types.h"
 #include "nnue_architecture.h"
@@ -35,11 +35,6 @@
 
 namespace Stockfish {
 class Position;
-
-namespace Eval {
-struct EvalFile;
-}
-
 }
 
 namespace Stockfish::Eval::NNUE {
@@ -87,9 +82,7 @@ bool                       save_eval(std::ostream&      stream,
                                      NetSize            netSize,
                                      const std::string& name,
                                      const std::string& netDescription);
-bool                       save_eval(const std::optional<std::string>& filename,
-                                     NetSize                           netSize,
-                                     const std::unordered_map<Eval::NNUE::NetSize, Eval::EvalFile>&);
+bool save_eval(const std::optional<std::string>& filename, NetSize netSize, const EvalFiles&);
 
 }  // namespace Stockfish::Eval::NNUE