Tests | Add collation transcoding tests

[edwardneal]

Description

This PR replaces one test and introduces another.

CollatedDataReaderTest

Previously, CollatedDataReaderTest would create a brand new database with one of two collations (Kazakh_90_CI_AI and Georgian_Modern_Sort_CI_AS), then try to select an ASCII string from it. This had a few issues:

• It only tested two collations and two code pages
• The permissions needed to create a new database precluded an Azure SQL instance
• The ASCII string was a very generous test case. It verified a string containing characters which are present in every code page

I've replaced this with something a little more robust. We now test every collation on a SQL instance, retrieving the character string and its byte representation, then we make sure that they roundtrip. It also uses a string containing the é character; this isn't present in Kazakh_90_CI_AI's code page, so SQL Server converts it to e. This is legitimate behaviour which would otherwise have failed.

CollatedStringInOutputParameter_DecodesSuccessfully

This is a new test which proves that we can roundtrip non-ASCII characters in output parameters when the value's collation's code page represents these non-ASCII characters differently: the default English Windows code page represents é as 0xE9; code page 936 represents this as [0xA8, 0xA6]; and UTF8 represents this as [0xC3, 0xA9].

Issues

Loosely related: #584 originally added the CollatedDataReaderTest test, and referred to making sure that the driver would maintain the collation/codepage mappings. These two tests provide sufficient test coverage for that effort (which would also unblock globalization invariant mode.)

Testing

New tests run, the other tests and code remain untouched.

[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 65.56%. Comparing base (14b96a2) to head (c4be946).
⚠️ Report is 48 commits behind head on main.

❗ There is a different number of reports uploaded between BASE (14b96a2) and HEAD (c4be946). Click for more details.

HEAD has 1 upload less than BASE

Flag	BASE (14b96a2)	HEAD (c4be946)
CI-SqlClient	1	0

Additional details and impacted files

@@            Coverage Diff             @@
##             main    #4051      +/-   ##
==========================================
- Coverage   74.62%   65.56%   -9.07%     
==========================================
  Files         280      274       -6     
  Lines       43814    66778   +22964     
==========================================
+ Hits        32698    43785   +11087     
- Misses      11116    22993   +11877     

Flag	Coverage Δ
CI-SqlClient	?
PR-SqlClient-Project	65.56% <ø> (?)

Flags with carried forward coverage won't be shown. Click here to find out more.

☔ View full report in Codecov by Sentry.
📢 Have feedback on the report? Share it here.

🚀 New features to boost your workflow:

• ❄️ Test Analytics: Detect flaky tests, report on failures, and find test suite problems.

[cheenamalhotra]

Very important test for encoding validation. Thanks!