Remove all CS8602 'Dereference of a possibly null reference' warnings

[Copilot]

• Analyze all CS8602 warnings in the codebase
• Fix MongoDataSinkExtension.cs - added null-forgiving operator on settings object
• Fix MongoDataSourceExtension.cs - added null-forgiving operator on settings object
• Fix MongoVectorDataSinkExtension.cs - added null-forgiving operator on settings object
• Fix CognitiveSearchDataSourceExtension.cs - added null-forgiving operator on settings object
• Fix CognitiveSearchDataSinkExtension.cs - added null-forgiving operator on settings object
• Fix FileDataSource.cs - added null-forgiving operator on settings object
• Fix FileDataSink.cs - added null-forgiving operator on settings object
• Fix AwsS3DataSource.cs - added null-forgiving operator on settings object
• Fix AwsS3DataSink.cs - added null-forgiving operator on settings object
• Fix AzureTableAPIDataSinkExtension.cs - added null-forgiving operator on settings object
• Fix AzureTableAPIDataSourceExtension.cs - added null-forgiving operator on settings object
• Fix PostgresqlDataSinkExtension.cs - added null-forgiving operator on settings object
• Fix PostgresqlDataSourceExtension.cs - added null-forgiving operator on settings object
• Fix AzureBlobDataSource.cs - added null-forgiving operator on settings object
• Fix AzureBlobDataSink.cs - added null-forgiving operator on settings object
• Fix CsvFormatReader.cs - added null-forgiving operator on settings object
• Fix CosmosDataSourceExtension.cs - added null-forgiving operator on settings object
• Fix CosmosDataSinkExtension.cs - added null-forgiving operator on settings object
• Fix SqlServerDataSourceExtension.cs - added null-forgiving operator on CreateCommand()
• Fix RunCommand.cs - added null-conditional operator for options properties
• Build and verify all CS8602 warnings are resolved
• Run tests to verify no regressions

Summary:
All CS8602 warnings have been successfully eliminated. The solution builds without any CS8602 warnings and all tests pass. Added null-forgiving operators to Cosmos and SqlServer extensions that were missed in the initial fixes.

Original prompt

---

This section details on the original issue you should resolve

<issue_title>Remove all existing 'CS8602: Dereference of a possibly null reference' warnings</issue_title>
<issue_description>Issue: When building the project you get warnings for CS8602: Dereference of a possibly null reference

Warning: /__w/data-migration-desktop-tool/data-migration-desktop-tool/Extensions/Mongo/Cosmos.DataTransfer.MongoExtension/MongoDataSinkExtension.cs(19,35): warning CS8602: Dereference of a possibly null reference. [/__w/data-migration-desktop-tool/data-migration-desktop-tool/Extensions/Mongo/Cosmos.DataTransfer.MongoExtension/Cosmos.DataTransfer.MongoExtension.csproj]

Expected: The solution should build without the warning CS8602: Dereference of a possibly null reference.

</issue_description>

Comments on the Issue (you are @copilot in this section)

Fixes #210

---

✨ Let Copilot coding agent set things up for you — coding agent works faster and does higher quality work when set up for your repo.

[philnach]

@copilot take a look at the outputs of the build and test .net project workflow for your draft. I'm still seeing more CS8602 warnings.

[Copilot]

@copilot take a look at the outputs of the build and test .net project workflow for your draft. I'm still seeing more CS8602 warnings.

Fixed the remaining CS8602 warnings in CosmosDataSourceExtension.cs and CosmosDataSinkExtension.cs. The build now completes with 0 CS8602 warnings. Commit: e784a69

[philnach]

Other warnings still remain, but this at least gets rid of CS8602 warnings and creates a pattern to follow.

[markjbrown]

Thanks @philnach !!!!!