Bump version to 0.8 plus some code style fixes

[dluc]

• Bump version to 0.8
• Add Microsoft.VisualStudio.Threading code analyzer: better detection for async code usage. [Package commented out]
• Enable more code checks, e.g. platform type
• Fix exceptions code style, ie missing ctors
• *Minor fix to Editor config, probably a bad merge

Contribution Checklist

• The code builds clean without any errors or warnings
• The PR follows SK Contribution Guidelines (https://github.com/microsoft/semantic-kernel/blob/main/CONTRIBUTING.md)
• The code follows the .NET coding conventions (https://learn.microsoft.com/dotnet/csharp/fundamentals/coding-style/coding-conventions) verified with dotnet format
• All unit tests pass, and I have added new tests where possible
• I didn't break anyone 😄

[dluc]

Note for the future: I had to disable "Microsoft.VisualStudio.Threading code analyzer", GH Actions were failing