Add VECTOR and BSON data types support

[okramarenko]

This PR introduces SingleStoreDbType.Vector and SingleStoreDbType.Bson, enables SingleStore extended protocol metadata by default on supported servers (adjustable via EnableExtendedDataTypes conn string parameter), and maps native VECTOR/BSON columns to appropriate .NET types.

Note

Medium Risk
Medium risk: introduces new protocol parsing and session initialization behavior (EnableExtendedDataTypes) that affects how column metadata/values and bulk copy parameter serialization work, with potential compatibility impact on older servers and existing binary/blob workflows.

Overview
Adds native VECTOR and BSON support via SingleStore extended protocol metadata, including new SingleStoreDbType.Bson/Vector mappings, typed VECTOR reads as ReadOnlyMemory<T>, and updated schema (SingleStoreDbColumn) metadata for dimensions/element type.

Introduces EnableExtendedDataTypes connection-string option (default true) that sets enable_extended_types_metadata on supported servers (8.5.28+) and falls back to legacy metadata unless explicitly required; ResetConnectionAsync now re-applies this session initialization.

Extends parameter inference/serialization and bulk copy handling for VECTOR/BSON (including correct casting expressions for SingleStoreBulkCopy), adds shared binary conversion utilities, and updates/expands docs and tests to cover round-trips, legacy-disable behavior, and bulk copy scenarios.

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[Copilot]

Pull request overview

This PR adds native SingleStore VECTOR and BSON support to the connector by enabling extended type metadata (via a new EnableExtendedDataTypes connection-string option) and updating type mapping, column metadata, value readers, parameter handling, and bulk copy casting to understand these types.

Changes:

• Introduces SingleStoreDbType.Vector / SingleStoreDbType.Bson, parses extended protocol metadata for these types, and returns VECTOR values as typed ReadOnlyMemory<T> while treating BSON as byte[].
• Adds session initialization (SET SESSION enable_extended_types_metadata = TRUE) controlled by EnableExtendedDataTypes (default true) with version-gated fallback/exception behavior.
• Extends parameter inference/serialization and SingleStoreBulkCopy mapping to correctly serialize/cast VECTOR/BSON; adds docs and expands tests for round-trips and bulk copy.

Reviewed changes

Copilot reviewed 28 out of 28 changed files in this pull request and generated 3 comments.

Show a summary per file

File	Description
tests/SingleStoreConnector.Tests/SingleStoreConnectionStringBuilderTests.cs	Updates tests for the new EnableExtendedDataTypes option default/parse/round-trip.
tests/SideBySide/StoredProcedureTests.cs	Adds a stored procedure test validating BSON result typing and value retrieval.
tests/SideBySide/ServerFeatures.cs	Adds ServerFeatures.ExtendedDataTypes feature flag.
tests/SideBySide/QueryTests.cs	Adds round-trip tests for VECTOR/BSON parameters and supported memory formats.
tests/SideBySide/ParameterTests.cs	Adds parameter inference tests for vector-like numeric arrays and extended db types.
tests/SideBySide/ExtendedDataTypeTestUtilities.cs	New helper utilities for asserting vector values across multiple data representations.
tests/SideBySide/DataTypesFixture.cs	Creates/populates VECTOR and BSON datatype tables when supported.
tests/SideBySide/DataTypes.cs	Adds schema and query tests for VECTOR/BSON, plus a legacy-metadata test when disabled.
tests/SideBySide/ConnectionTests.cs	Adds reset-connection test ensuring extended types session state is preserved.
tests/SideBySide/BulkLoaderSync.cs	Adds bulk copy tests for VECTOR/BSON using DataTable and DataReader (sync).
tests/SideBySide/BulkLoaderAsync.cs	Adds bulk copy tests for VECTOR/BSON using DataTable (async).
src/SingleStoreConnector/SingleStoreParameter.cs	Adds inference/serialization paths for VECTOR/BSON; refactors binary literal writing and vector literal creation.
src/SingleStoreConnector/SingleStoreDbType.cs	Adds Bson and Vector provider/logical types.
src/SingleStoreConnector/SingleStoreDbColumn.cs	Surfaces vector dimension/element type schema metadata and adjusts DataType/DataTypeName for extended types.
src/SingleStoreConnector/SingleStoreConnectionStringBuilder.cs	Adds EnableExtendedDataTypes connection-string option.
src/SingleStoreConnector/SingleStoreConnection.cs	Adds session initialization to enable extended metadata on supported servers and re-applies it on reset.
src/SingleStoreConnector/SingleStoreBulkCopy.cs	Adds VECTOR/BSON column mappings using UNHEX(...):>VECTOR(...) and UNHEX(...):>BSON, plus broader vector input support.
src/SingleStoreConnector/Protocol/Payloads/ColumnDefinitionPayload.cs	Parses extended type metadata from column definitions (type code, vector dimensions/element type).
src/SingleStoreConnector/Protocol/ColumnType.cs	Clarifies that BSON/VECTOR are exposed via extended metadata, not new base column types.
src/SingleStoreConnector/Core/TypeMapper.cs	Adds type metadata for BSON/VECTOR and maps extended type codes to provider types.
src/SingleStoreConnector/Core/SingleStoreBinaryValueConverter.cs	New shared converter for BSON raw bytes and vector element-to-byte conversion plus inference helpers.
src/SingleStoreConnector/Core/ServerVersions.cs	Adds SupportsExtendedDataTypes server version gate (8.5.28+).
src/SingleStoreConnector/Core/Row.cs	Updates binary column checks to allow BSON but disallow VECTOR-to-bytes casts.
src/SingleStoreConnector/Core/ConnectionSettings.cs	Plumbs EnableExtendedDataTypes and “explicitly set” detection into settings.
src/SingleStoreConnector/ColumnReaders/VectorColumnReader.cs	New typed readers for vector element types with length/endianness validation.
src/SingleStoreConnector/ColumnReaders/ColumnReader.cs	Routes extended types to appropriate readers (BytesColumnReader for BSON; vector readers for VECTOR).
docs/content/tutorials/best-practices.md	Documents how to read/write VECTOR/BSON and the EnableExtendedDataTypes option.
docs/content/connection-options.md	Adds EnableExtendedDataTypes connection option documentation and behavior details.

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