CSHARP-5717: Introduce basic vector enum types

As discussed with Boris, these are used for index building in EF Core. There isn't any strongly typed API for vector indexes in the driver yet, but, when there is, then these enums will be used there as well as being used by EF.

Author: ajcvickers

src/MongoDB.Driver/VectorQuantization.cs

@@ -0,0 +1,43 @@
+/* Copyright 2010-present MongoDB Inc.
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ * http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+
+namespace MongoDB.Driver
+{
+    /// <summary>
+    /// Type of automatic vector quantization for your vectors. Use this setting only if your embeddings are float
+    /// or double vectors. See <see href="https://www.mongodb.com/docs/atlas/atlas-vector-search/vector-quantization/">
+    /// Vector Quantization</see> for more information.
+    /// </summary>
+    public enum VectorQuantization
+    {
+        /// <summary>
+        /// Indicates no automatic quantization for the vector embeddings. Use this setting if you have pre-quantized
+        /// vectors for ingestion. If omitted, this is the default value.
+        /// </summary>
+        None,
+
+        /// <summary>
+        /// Indicates scalar quantization, which transforms values to 1 byte integers.
+        /// </summary>
+        Scalar,
+
+        /// <summary>
+        /// Indicates binary quantization, which transforms values to a single bit.
+        /// To use this value, numDimensions must be a multiple of 8.
+        /// If precision is critical, select <see cref="None"/> or <see cref="Scalar"/> instead of <see cref="Binary"/>.
+        /// </summary>
+        Binary,
+    }
+}

src/MongoDB.Driver/VectorSimilarity.cs

@@ -0,0 +1,40 @@
+/* Copyright 2010-present MongoDB Inc.
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ * http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+
+namespace MongoDB.Driver
+{
+    /// <summary>
+    /// Vector similarity function to use to search for top K-nearest neighbors.
+    /// See <see href="https://www.mongodb.com/docs/atlas/atlas-vector-search/vector-search-type/">How to Index Fields for
+    /// Vector Search</see> for more information.
+    /// </summary>
+    public enum VectorSimilarity
+    {
+        /// <summary>
+        /// Measures the distance between ends of vectors.
+        /// </summary>
+        Euclidean,
+
+        /// <summary>
+        /// Measures similarity based on the angle between vectors.
+        /// </summary>
+        Cosine,
+
+        /// <summary>
+        /// mMasures similarity like cosine, but takes into account the magnitude of the vector.
+        /// </summary>
+        DotProduct,
+    }
+}