Fix Nuget references and create .nuspec files

[mrsalmon1976]

Nuget has moved on since this project was created but the package deployment script has never been changed. See below trace for warnings and errors that need to be resolved.

MSBuild auto-detection: using msbuild version '17.4.1.60106' from 'C:\Program Files\Microsoft Visual Studio\2022\Professional\MSBuild\Current\bin'.
Packing files from 'C:\Matt\code\Stateless.WorkflowEngine\source\Stateless.WorkflowEngine\bin\Debug\netstandard2.0'.
WARNING: NU5115: Description was not specified. Using 'Description'.
WARNING: NU5115: Author was not specified. Using 'matt'.
WARNING: NU5128: Some target frameworks declared in the dependencies group of the nuspec and the lib/ref folder do not have exact matches in the other location. Consult the list of actions below:
- Add a dependency group for .NETStandard2.0 to the nuspec
Successfully created package 'C:\Matt\code\Stateless.WorkflowEngine\source\Stateless.WorkflowEngine\Stateless.WorkflowEngine.3.0.0.nupkg'.
Pushing Stateless.WorkflowEngine.3.0.0.nupkg to 'https://www.nuget.org/api/v2/package'...
  PUT https://www.nuget.org/api/v2/package/
  Conflict https://www.nuget.org/api/v2/package/ 1963ms
To skip already published packages, use the option -SkipDuplicate
Response status code does not indicate success: 409 (A package with ID 'Stateless.WorkflowEngine' and version '3.0.0' already exists and cannot be modified.).
Attempting to build package from 'Stateless.WorkflowEngine.MongoDb.csproj'.
MSBuild auto-detection: using msbuild version '17.4.1.60106' from 'C:\Program Files\Microsoft Visual Studio\2022\Professional\MSBuild\Current\bin'.
Packing files from 'C:\Matt\code\Stateless.WorkflowEngine\source\Stateless.WorkflowEngine.MongoDb\bin\Debug\netstandard2.0'.
WARNING: NU5118: File 'C:\Matt\code\Stateless.WorkflowEngine\source\Stateless.WorkflowEngine.MongoDb\bin\Debug\netstandard2.0\publish\Stateless.WorkflowEngine.MongoDb.dll' is 
not added because the package already contains file 'lib\netstandard2.0\Stateless.WorkflowEngine.MongoDb.dll'
WARNING: NU5118: File 'C:\Users\matt\.nuget\packages\mongodb.libmongocrypt\1.7.0\runtimes\win\native\mongocrypt.dll' is not added because the package already contains file 'content\mongocrypt.dll'
WARNING: NU5115: Description was not specified. Using 'Description'.
WARNING: NU5115: Author was not specified. Using 'matt'.
WARNING: NU5100: The assembly 'content\mongocrypt.dll' is not inside the 'lib' folder and hence it won't be added as a reference when the package is installed into a project. 
Move it into the 'lib' folder if it needs to be referenced.
WARNING: NU5128: Some target frameworks declared in the dependencies group of the nuspec and the lib/ref folder do not have exact matches in the other location. Consult the list of actions below:
- Add a dependency group for .NETStandard2.0 to the nuspec
Successfully created package 'C:\Matt\code\Stateless.WorkflowEngine\source\Stateless.WorkflowEngine.MongoDb\Stateless.WorkflowEngine.MongoDb.3.0.0.nupkg'.
Pushing Stateless.WorkflowEngine.MongoDb.3.0.0.nupkg to 'https://www.nuget.org/api/v2/package'...
  PUT https://www.nuget.org/api/v2/package/
  Conflict https://www.nuget.org/api/v2/package/ 10586ms
To skip already published packages, use the option -SkipDuplicate
Response status code does not indicate success: 409 (A package with ID 'Stateless.WorkflowEngine.MongoDb' and version '3.0.0' already exists and cannot be modified.).```