Consistent Integer Types

example of using, to avoid mixed usage of std::uint/std::int and uint/int...
```cpp
using u64 = std::uint64_t;
using u32 = std::uint32_t;
using u16 = std::uint16_t;
using u8  = std::uint8_t;

using i64 = std::int64_t;
using i32 = std::int32_t;
using i16 = std::int16_t;
using i8  = std::int8_t;

using usize = std::size_t;
using isize = std::ptrdiff_t;

#if defined(__GNUC__) && defined(IS_64BIT)
__extension__ using u128 = unsigned __int128;
__extension__ using i128 = signed __int128;
#endif
```

closes https://github.com/official-stockfish/Stockfish/pull/6874

No functional change

src/timeman.cpp

@@ -21,7 +21,6 @@
 #include <algorithm>
 #include <cassert>
 #include <cmath>
-#include <cstdint>
 
 #include "search.h"
 #include "ucioption.h"
@@ -35,9 +34,9 @@ void TimeManagement::clear() {
     availableNodes = -1;  // When in 'nodes as time' mode
 }
 
-void TimeManagement::advance_nodes_time(std::int64_t nodes) {
+void TimeManagement::advance_nodes_time(i64 nodes) {
     assert(useNodesTime);
-    availableNodes = std::max(int64_t(0), availableNodes - nodes);
+    availableNodes = std::max(i64(0), availableNodes - nodes);
 }
 
 // Called at the beginning of the search and calculates
@@ -83,7 +82,7 @@ void TimeManagement::init(Search::LimitsType& limits,
 
     // These numbers are used where multiplications, divisions,
     // or comparisons with constants are involved.
-    const int64_t   scaleFactor = useNodesTime ? npmsec : 1;
+    const i64       scaleFactor = useNodesTime ? npmsec : 1;
     const TimePoint scaledTime  = limits.time[us] / scaleFactor;
 
     // Maximum move horizon