Add 2023 R2 gRPC transport (RemoteGrpc) reusing native byte payloads

Stands up HistorianTransport.RemoteGrpc end-to-end for the read path,
built on the recovered 2023 R2 gRPC contract (gRPC-Web/HTTP-1.1, port
32565, gzip). The opaque protobuf `bytes` fields carry the SAME native
binary payloads as the 2020 WCF/MDAS path, so the proven serializers and
parsers are reused unchanged.

- Grpc/Protos/*.proto: 6 protoc-validated contracts recovered from
  embedded FileDescriptors (authoritative, not guessed).
- Grpc/HistorianGrpcChannelFactory: GrpcWebHandler/HTTP-1.1 channel,
  ResolvePort/ResolveAddress, optional TLS + gzip.
- Grpc/HistorianGrpcReadOrchestrator: mirrors the WCF read chain over
  gRPC; auth uses HistoryService.ExchangeKey (the gRPC ValCl op).
- Wcf/HistorianNativeHandshake: transport-agnostic Open2 request builder
  + SSPI/Negotiate token loop + response decode, shared by WCF and gRPC.
- Op map (2020 -> gRPC): ValCl->ExchangeKey, Open2->OpenConnection,
  StartQuery2->StartQuery, GetNextQueryResultBuffer2->GetNextQueryResultBuffer.
- HistorianClientOptions: DefaultGrpcPort=32565, GrpcUseTls.
- csproj: Google.Protobuf, Grpc.Net.Client(.Web), Grpc.Tools codegen.

Not yet live-verified against a 2023 R2 server: ExchangeKey is the first
thing to revisit if a live server rejects the handshake; the inner byte
payloads are the proven 2020 protocol. Gated live test via
HISTORIAN_GRPC_HOST. 188 unit tests green; build clean.

Co-Authored-By: Claude Opus 4.8 (1M context) <noreply@anthropic.com>

src/AVEVA.Historian.Client/Wcf/HistorianWcfReadOrchestrator.cs

@@ -371,7 +371,7 @@ internal sealed class HistorianWcfReadOrchestrator
         }
     }
 
-    private static HistorianDataQueryRequest BuildDataQueryRequest(string tag, DateTime startUtc, DateTime endUtc, int maxValues)
+    internal static HistorianDataQueryRequest BuildDataQueryRequest(string tag, DateTime startUtc, DateTime endUtc, int maxValues)
     {
         return new HistorianDataQueryRequest(
             TagNames: [tag],
@@ -382,7 +382,7 @@ internal sealed class HistorianWcfReadOrchestrator
             Option: string.Empty);
     }
 
-    private static HistorianDataQueryRequest BuildAggregateQueryRequest(
+    internal static HistorianDataQueryRequest BuildAggregateQueryRequest(
         string tag,
         DateTime startUtc,
         DateTime endUtc,
@@ -427,7 +427,7 @@ internal sealed class HistorianWcfReadOrchestrator
         return (uint)mode;
     }
 
-    private static uint MapRetrievalModeToAggregationType(Models.RetrievalMode mode) => mode switch
+    internal static uint MapRetrievalModeToAggregationType(Models.RetrievalMode mode) => mode switch
     {
         Models.RetrievalMode.TimeWeightedAverage => 0,
         Models.RetrievalMode.Interpolated => 3,