Inline GetAlternateLookup

[bitfaster]

Inlining GetAlternateLookup eliminates the heap allocation for the AlternateLookup struct on .NET 10:

Method	Runtime	Mean	Ratio	Gen0	Allocated
GetAlternateInline	.NET 10.0	42.73 ns	0.77	-	-
GetAlternateNoInline	.NET 10.0	52.94 ns	0.96	0.0092	40 B
GetAlternateInline	.NET 9.0	55.35 ns	1.00	0.0092	40 B
GetAlternateNoInline	.NET 9.0	56.13 ns	1.01	0.0092	40 B

[coveralls]

coverage: 99.066% (-0.04%) from 99.11% — users/alexpeck/inline10 into main