Remove warning CS1701 and CS1702 when using RoslynCodeTaskFactory

[huulinhnguyen-dev]

Fixes #
Fix the issue: Suppress CS1701 and CS1702 warnings by default in RoslynCodeTaskFactory to align with .NET SDK #12101

Context

When using RoslynCodeTaskFactory, MSBuild emits CS1701 and CS1702 assembly binding warnings for version mismatches (e.g., between System.Memory and System.Text.Json). These warnings are not actionable in modern .NET scenarios and are already suppressed by default in the .NET SDK and Roslyn. This issue causes unnecessary warning noise and confusion in custom task or non-SDK builds.

Changes Made

Added a new property in the task factory configuration to include NoWarn="1701;1702" for all tasks generated by RoslynCodeTaskFactory

Testing

Added a new unit test RoslynCodeTaskFactoryWithoutCS1702Warning in the MSBuild test suite to verify that no CS1702 warnings are emitted when using RoslynCodeTaskFactory with references to System.Memory (v4.6.3) and System.Text.Json (v9.0.7).

Create a project file base on example of user for test dotnet/roslyn#19640 (comment)

Notes

[JanProvaznik]

Please don't commit the package dlls and xml files to the repo... This would increase maintenace burden and potentially cause security flagging in the future.