Remove obsolete Observation class and ToProto() function (#4499)

Remove obsolete Observation class and ToProto() function

com.unity.ml-agents/Runtime/Communicator/GrpcExtensions.cs

         #endregion
 
         #region Observations
-        public static ObservationProto ToProto(this Observation obs)
-        {
-            ObservationProto obsProto = null;
-
-            if (obs.CompressedData != null)
-            {
-                // Make sure that uncompressed data is empty
-                if (obs.FloatData.Count != 0)
-                {
-                    Debug.LogWarning("Observation has both compressed and uncompressed data set. Using compressed.");
-                }
-
-                obsProto = new ObservationProto
-                {
-                    CompressedData = ByteString.CopyFrom(obs.CompressedData),
-                    CompressionType = (CompressionTypeProto)obs.CompressionType,
-                };
-            }
-            else
-            {
-                var floatDataProto = new ObservationProto.Types.FloatData
-                {
-                    Data = { obs.FloatData },
-                };
-
-                obsProto = new ObservationProto
-                {
-                    FloatData = floatDataProto,
-                    CompressionType = (CompressionTypeProto)obs.CompressionType,
-                };
-            }
-
-            obsProto.Shape.AddRange(obs.Shape);
-            return obsProto;
-        }
-
         /// <summary>
         /// Static flag to make sure that we only fire the warning once.
         /// </summary>

com.unity.ml-agents/Runtime/Sensors/Observation.cs.meta

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com.unity.ml-agents/Runtime/Sensors/Observation.cs

-using System;
-
-namespace Unity.MLAgents.Sensors
-{
-    internal struct Observation
-    {
-        /// <summary>
-        /// The compressed sensor data. Assumed to be non-null if CompressionType != CompressionType.None
-        /// </summary>
-        public byte[] CompressedData;
-
-        /// <summary>
-        /// Uncompressed sensor data. Assumed to be non-empty if CompressionType == CompressionType.None
-        /// </summary>
-        public ArraySegment<float> FloatData;
-
-        /// <summary>
-        /// The format of the compressed data
-        /// </summary>
-        public SensorCompressionType CompressionType;
-
-        /// <summary>
-        /// The uncompressed dimensions of the data.
-        /// E.g. for RGB visual observations, this will be {Height, Width, 3}
-        /// </summary>
-        public int[] Shape;
-    }
-}