[csharp][generichost] Better file support #29

Job	Run time
Build clients (samples/client/petstore/csharp/restsharp/net8/ParameterMappings/)	1m 55s
Build clients (samples/client/petstore/csharp/restsharp/net4.7/Petstore/)	1m 38s
Build clients (samples/client/petstore/csharp/restsharp/net4.7/MultipleFrameworks/)	2m 13s
Build clients (samples/client/petstore/csharp/restsharp/net4.8/Petstore/)	1m 40s
Build clients (samples/client/petstore/csharp/restsharp/net8/EnumMappings/)	1m 34s
Build clients (samples/client/petstore/csharp/restsharp/net8/UseDateTimeForDate/)	1m 32s
Build clients (samples/client/petstore/csharp/restsharp/net8/Petstore/)	1m 54s
Build clients (samples/client/petstore/csharp/restsharp/standard2.0/ConditionalSerialization/)	2m 3s
	14m 29s

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