[csharp][generichost] Better file support #38

Job	Run time
Build clients (samples/client/petstore/csharp/restsharp/net8/ParameterMappings/)	2m 30s
Build clients (samples/client/petstore/csharp/restsharp/net4.8/Petstore/)	2m 11s
Build clients (samples/client/petstore/csharp/restsharp/net8/UseDateTimeForDate/)	1m 35s
Build clients (samples/client/petstore/csharp/restsharp/standard2.0/ConditionalSerialization/)	2m 22s
Build clients (samples/client/petstore/csharp/restsharp/net4.7/Petstore/)	1m 39s
Build clients (samples/client/petstore/csharp/restsharp/net8/EnumMappings/)	1m 46s
Build clients (samples/client/petstore/csharp/restsharp/net4.7/MultipleFrameworks/)	2m 23s
Build clients (samples/client/petstore/csharp/restsharp/net8/Petstore/)	2m 4s
	16m 30s

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