feat: add suppressor of CA1707 for test methods

[Flash0ver]

closes #96

Changes

• add suppressor to allow underscores in well-known unit test methods
  • update Microsoft.CodeAnalysis.Testing packages
  • add Testing types for DiagnosticSuppressors
    • see also Improve support for DiagnosticSuppressor dotnet/roslyn-sdk#942
  • add Benchmarking types for DiagnosticSuppressors
  • add unit test example project
• enable all .NET analyzers for all projects
  • suppress some rules via .globalconfig if not applicable to project type
• fix false positives of Microsoft.CodeAnalysis.Analyzers
  • RS1024, see False positive for RS1024 when using ToDictionary(...) dotnet/roslyn-analyzers#5715
  • RS2003, see Release tracking analyzer doesn't recognize target-typed new dotnet/roslyn-analyzers#5828
• some other cleanup and formatting
  • i.a. use trailing comma in object initializers, to make future changes git history friendly

Facts

• DiagnosticSuppressors are available since Roslyn 3.3.1

[TimoHeiten]

Looks good to me. Tbh I cannot check for the domain at this place & time because I do not understand what´s going on :D

As a remark:
there are some places where you use the same method call with pretty much the same parameters (string equals with ordinal or stringbuilder with \t- as prefix etc.)
Maybe create a local function so you dont have to copy paste everything if it might change. DRY but its absolutely a non issue and only my personal style.

[Flash0ver]

Thanks for your reviews and feedback.

During deduplicating, I actually found that I've missed two Ordinal string comparisons via StartsWith previously, which I think did then a StringComparison.CurrentCulture comparison.