feat(csharp): Add driver manager

csharp/src/Apache.Arrow.Adbc/Apache.Arrow.Adbc.csproj

@@ -16,6 +16,11 @@
     <Compile Remove="C\NativeLibrary.cs" />
   </ItemGroup>
   <ItemGroup>
+    <Content Include="DriverManager\readme.md">
+      <PackagePath>\</PackagePath>
+      <CopyToOutputDirectory>PreserveNewest</CopyToOutputDirectory>
+      <Pack>true</Pack>
+    </Content>
     <Content Include="readme.md">
       <Pack>true</Pack>
       <PackagePath>\</PackagePath>

csharp/src/Apache.Arrow.Adbc/DriverManager/AdbcLoadFlags.cs

@@ -0,0 +1,63 @@
+/*
+ * Licensed to the Apache Software Foundation (ASF) under one or more
+ * contributor license agreements.  See the NOTICE file distributed with
+ * this work for additional information regarding copyright ownership.
+ * The ASF licenses this file to You 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.
+ */
+
+using System;
+
+namespace Apache.Arrow.Adbc.DriverManager
+{
+    /// <summary>
+    /// Flags to control how the ADBC driver manager searches for and loads drivers.
+    /// Mirrors the <c>AdbcLoadFlags</c> type and <c>ADBC_LOAD_FLAG_*</c> constants
+    /// defined in <c>adbc_driver_manager.h</c>.
+    /// </summary>
+    [Flags]
+    public enum AdbcLoadFlags : uint
+    {
+        /// <summary>No search flags set.</summary>
+        None = 0,
+
+        /// <summary>
+        /// Search the <c>ADBC_DRIVER_PATH</c> environment variable for drivers.
+        /// Corresponds to <c>ADBC_LOAD_FLAG_SEARCH_ENV</c>.
+        /// </summary>
+        SearchEnv = 1,
+
+        /// <summary>
+        /// Search the user-level configuration directory for drivers.
+        /// Corresponds to <c>ADBC_LOAD_FLAG_SEARCH_USER</c>.
+        /// </summary>
+        SearchUser = 2,
+
+        /// <summary>
+        /// Search the system-level configuration directory for drivers.
+        /// Corresponds to <c>ADBC_LOAD_FLAG_SEARCH_SYSTEM</c>.
+        /// </summary>
+        SearchSystem = 4,
+
+        /// <summary>
+        /// Allow loading drivers from relative paths.
+        /// Corresponds to <c>ADBC_LOAD_FLAG_ALLOW_RELATIVE_PATHS</c>.
+        /// </summary>
+        AllowRelativePaths = 8,
+
+        /// <summary>
+        /// Default flags: search env, user, system, and allow relative paths.
+        /// Corresponds to <c>ADBC_LOAD_FLAG_DEFAULT</c>.
+        /// </summary>
+        Default = SearchEnv | SearchUser | SearchSystem | AllowRelativePaths,
+    }
+}