Merge | Port SqlDataSourceConverter, widen test coverage (dotnet#3309)

* Port type converter for DataSource, FailoverPartner

Also add test coverage for this type converter (and for the netfx-only NetworkLibraryConverter.)

* Tests: pass DescriptorContext to InitialCatalogConverter.GetStandardValuesSupported

Port localizations for the new SNI_ERROR_10 code from PR dotnet#3284 (d…

…otnet#3308)

Added localizations for the new SNI_ERROR_10 code from PR dotnet#3284.

MDS Release v5.1.7

[6.0] Port localization string changes (dotnet#3296)

Port dotnet#3126 to release/6.0 (dotnet#3127)

* Fix down-level SSL/TLS version warnings (dotnet#3126)

* Added test for downlevel connectivity warning

* Correctly test bit flags for legacy SSL protocol warning

* Corrected warning disablement/restore.

(cherry picked from commit 198b906)

* Test by rolling back changes to connection test matrix

---------

Co-authored-by: Edward Neal <[email protected]>

Tagging for 6.0.0-preview3 release.

Merge branch 'main' into dev/cheena/pull-main

Doc | Release notes v6.0 preview1 (dotnet#2813)

[5.1] Eng | Add strong name validation to package validator (dotnet#2802

) (dotnet#2804)

[5.2.2] | Fix decrypt failure to drain data (dotnet#2618) (dotnet#2817)