Add ability to disable performance-sensitive relaxed atomic operations at compile time

Adds a `RelaxedAtomic`  wrapper around either `T` or `std::atomic<T>` and `USE_SLOPPY_ATOMICS` preprocessor define. The intent of this flag is to allow easy disabling of atomics on WASM, where even relaxed atomics are expensive because all atomics have `seq_cst` semantics.

Passed non regression STC
LLR: 2.99 (-2.94,2.94) <-1.75,0.25>
Total: 50624 W: 12976 L: 12776 D: 24872
Ptnml(0-2): 112, 5445, 14005, 5631, 119
https://tests.stockfishchess.org/tests/view/6a1f690e818cacc1db0ad2c7

Passed non-regression STC SMP
 LLR: 2.94 (-2.94,2.94) <-1.75,0.25>
Total: 163696 W: 41514 L: 41438 D: 80744
Ptnml(0-2): 162, 18272, 44904, 18348, 162
https://tests.stockfishchess.org/tests/view/6a21fb97351b79f679cc44b3

Using this class for the TT also allows us to remove the TSAN suppressions, since the UB is fixed.

closes https://github.com/official-stockfish/Stockfish/pull/6877

No functional change

tests/instrumented.py

@@ -8,7 +8,6 @@ import fnmatch
 
 from testing import (
     EPD,
-    TSAN,
     Stockfish as Engine,
     MiniTestFramework,
     OrderedClassMembers,
@@ -591,7 +590,6 @@ if __name__ == "__main__":
     args = parse_args()
 
     EPD.create_bench_epd()
-    TSAN.set_tsan_option()
     Syzygy.download_syzygy()
 
     framework = MiniTestFramework()
@@ -600,7 +598,6 @@ if __name__ == "__main__":
     framework.run([TestCLI, TestInteractive, TestSyzygy, TestEnPassantSanitization])
 
     EPD.delete_bench_epd()
-    TSAN.unset_tsan_option()
 
     if framework.has_failed():
         sys.exit(1)