Modify SqlStreamingXml XmlWriter to internally use a MemoryStream

[jimhblythe]

Modify SqlStreamingXml XmlWriter to internally use a MemoryStream instead of a StringBuilder.

Note: UTF8Encoding(false) addition in s_writerSettings is consistent with prior default used within StringWriter/StringBuilder

Issues

Fixes #1877 to be O(n)

Testing

Added 2 new Manual tests to ensure linear behavior for single large node, and secondary validation for multiple nodes

[jimhblythe]

@dotnet-policy-service agree

[paulmedynski]

/azp run

[azure-pipelines]

Azure Pipelines successfully started running 2 pipeline(s).

[paulmedynski]

Looks great - thanks for this optimization and expanded test coverage! Just one question.

[paulmedynski]

/azp run

[azure-pipelines]

Azure Pipelines successfully started running 2 pipeline(s).

[codecov]

Codecov Report

✅ All modified and coverable lines are covered by tests.
✅ Project coverage is 64.59%. Comparing base (a68e00f) to head (9f44ae8).
⚠️ Report is 24 commits behind head on main.

❗ There is a different number of reports uploaded between BASE (a68e00f) and HEAD (9f44ae8). Click for more details.

HEAD has 6 uploads less than BASE

Flag	BASE (a68e00f)	HEAD (9f44ae8)
netfx	2	0
netcore	2	0
addons	2	0

Additional details and impacted files

@@             Coverage Diff             @@
##             main    #3974       +/-   ##
===========================================
- Coverage   75.22%   64.59%   -10.63%     
===========================================
  Files         266      282       +16     
  Lines       42932    66080    +23148     
===========================================
+ Hits        32294    42683    +10389     
- Misses      10638    23397    +12759     

Flag	Coverage Δ
PR-SqlClient-Project	64.59% <100.00%> (?)
addons	?
netcore	?
netfx	?

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[mdaigle]

@jimhblythe can you take a look at the tests in #4005 and #4008? They seem to suggest that this introduces a regression for non-ascii characters. You can check the pipeline results to see the test outcomes. I'd like to see some tests like that included in this PR as well, please 🙏

[jimhblythe]

@jimhblythe can you take a look at the tests in #4005 and #4008? They seem to suggest that this introduces a regression for non-ascii characters. You can check the pipeline results to see the test outcomes. I'd like to see some tests like that included in this PR as well, please 🙏

I will additionally including a fourth test to verify surrogate pairs:

        [ConditionalFact(typeof(DataTestUtility), nameof(DataTestUtility.AreConnStringsSetup))]
        public static void GetChars_SurrogatePairContent()
        {
            SqlConnection connection = new(DataTestUtility.TCPConnectionString);
            // Surrogate Pair characters: 4 bytes each in UTF-8
            string xml = "<data>\U0001F600\U0001F525\U0001F680</data>";

Actual: "<data>😀🔥🚀</data>"

The test shows these worked with prior code.