v1.25.1-beta1

• Fix csharp.unitTestDebuggingOptions description (#5309, PR: #5315)
• Removed quoted examples from omnisharp.sdkVersion and omnisharp.sdkPath (omnisharp-roslyn#2412, PR: #5301)
• Added an example on how to launch swagger ui (PR: #5283)
• Package manager nullability fixes (PR: #5255)
• Return all launch targets when maxProjectResults is set to 0 (#5227, PR: #5241)
• Clear nullability warnings (PR: #5236)
• Provide actionable error messages for .NET SDK issues (#5223, PR: #5225)
• Update OmniSharp to 1.39.1 (PR: #5319)
  • Update Roslyn to 4.4.0 1.22369.1 (PR: omnisharp-roslyn#2420)
  • Simplify some code (PR: omnisharp-roslyn#2370)
  • Return meaningful error when pinned SDK version is not found. (#5128, PR: omnisharp-roslyn#2403)
  • Added support for <WarningsAsErrors>nullable</WarningsAsErrors> (omnisharp-roslyn#2292, PR: omnisharp-roslyn#2406)
  • Removed nuget versioning reference from OmniSharp.Abstractions (omnisharp-roslyn#2410, PR: omnisharp-roslyn#2414)
  • Bump Newtonsoft.Json to 13.0.1 (PR: omnisharp-roslyn#2415)