Replace XmlWriter/MemoryStream with direct XmlReader parsing in SqlStreamingXml, reconstructing XML fragments as strings and streaming them char-by-char. Improves efficiency, reduces allocations, and fixes non-ASCII and surrogate pairs.

Add comprehensive unit tests for XML edge cases (non-ASCII, surrogate pairs, comments, CDATA, attributes, namespaces, etc.). Refactor existing tests for clarity and better handling of disposables.
(AI assist using ChatGPT to better consider edge cases)

Author: jimhblythe