Improved ToString() performance.

[jscarle]

BenchmarkDotNet v0.13.12, Windows 11 (10.0.22631.3155/23H2/2023Update/SunValley3)
13th Gen Intel Core i7-13700KF, 1 CPU, 24 logical and 16 physical cores
.NET SDK 8.0.200
  [Host]   : .NET 8.0.2 (8.0.224.6711), X64 RyuJIT AVX2
  .NET 8.0 : .NET 8.0.2 (8.0.224.6711), X64 RyuJIT AVX2
Iterations : 100 000

Method	Before	After	Before	After
ResultBaseIndexer	26.06 us	26.33 us	-	-
ResultBaseHasError	89.81 us	90.63 us	-	-
ResultOkToString	3,043.52 us	27.78 us	28800370 B	-
ResultFailToString	3,232.66 us	74.86 us	28800370 B	-
ResultFailWithMessageToString	6,744.95 us	2,837.31 us	69600892 B	24800002 B
ResultTValueOkToString	4,398.32 us	2,556.12 us	47200003 B	15200002 B
ResultTValueFailToString	2,601.94 us	74.39 us	28800002 B	-
ResultTValueFailWithMessageToString	6,339.77 us	2,743.11 us	69600003 B	24800002 B
CustomResultOkToString	4,409.29 us	1,880.67 us	43200577 B	8800118 B
CustomResultFailToString	4,529.00 us	2,220.69 us	44000588 B	9600129 B
CustomResultFailWithMessageToString	6,743.94 us	2,797.87 us	71200949 B	26400352 B
ResultOk	18.76 us	18.75 us	-	-
ResultFail	18.77 us	18.78 us	-	-
ResultFailWithError	535.57 us	540.72 us	8000000 B	8000000 B
ResultTValueOk	191.08 us	193.06 us	3200000 B	3200000 B
ResultTValueFail	18.75 us	18.73 us	-	-
ResultTValueFailWithError	549.88 us	551.19 us	8800000 B	8800000 B
ResultOkTValue	191.63 us	190.97 us	3200000 B	3200000 B
ResultFailTValue	18.75 us	18.74 us	-	-
ResultFailWithErrorTValue	556.70 us	548.32 us	8800000 B	8800000 B
NewError	223.62 us	222.60 us	3200000 B	3200000 B
NewErrorWithString	222.42 us	222.99 us	3200000 B	3200000 B