fix(csharp): use case-insensitive comparer when merging connection properties

This fixes a bug where properties passed via Connect() options weren't being found
in StatementExecutionStatement because the merged dictionary was using case-sensitive
comparison instead of case-insensitive.

Without this fix, parameters like ResultDisposition weren't being applied correctly.

Author: Jade Wang

csharp/src/DatabricksDatabase.cs

@@ -49,7 +49,7 @@ public override AdbcConnection Connect(IReadOnlyDictionary<string, string>? opti
                     ? properties
                     : options
                         .Concat(properties.Where(x => !options.Keys.Contains(x.Key, StringComparer.OrdinalIgnoreCase)))
-                        .ToDictionary(kvp => kvp.Key, kvp => kvp.Value);
+                        .ToDictionary(kvp => kvp.Key, kvp => kvp.Value, StringComparer.OrdinalIgnoreCase);
 
                 // Check protocol parameter to determine which connection type to create
                 string protocol = "thrift"; // Default to Thrift for backward compatibility