Add StyleCopAnalyzers to main projects

[AMCN41R]

Add StyleCopAnalyzers nuget package and associated configuration to main projects:

• ModelGenerator
• NHapi.Base
• NHapi.SourceGeneration
• NHapi.NUnit.SourceGeneration

Requierd configuration files:

• stylecop.json
• .editorconfig file
• omnisharp.json (for VS code support)

These files can be stored at the solution level, and refrenced by each project.

Default rules can be found here...

Linked to #124

[AMCN41R]

@milkshakeuk @duaneedwards - if you guys have any specific style preferences, lets document here?

[milkshakeuk]

Sounds good to me, I don't have a preference so I would recommend the microsoft standard rules, you can probably obtain an .editorconfig from one of their repos.

[AMCN41R]

https://docs.microsoft.com/en-us/dotnet/fundamentals/code-analysis/code-style-rule-options

[milkshakeuk]

The one thing I would say is that any public members which might clash against the naming rules, should be ignored to begin with this otherwise we will break the API contract.

My plan with this is to have 2 (new correctly styled members) and the old ones remain with Obsolete attributes applied. These can be removed in a future major revision.

[AMCN41R]

Yep. Agreed.

[AMCN41R]

StyleCop.Analyzers has a rule for file headers, SA1633, that is enabled by default.

Do you want this in each file? If not, we can globally disable the rule.

I'm happy either way.

[milkshakeuk]

I think this one can probably be turned off, unless @duaneedwards has any issues with this.

[duaneedwards]

No issues with turning this off from my side

[AMCN41R]

#143

[milkshakeuk]

@AMCN41R I think this is covered by #143 so ill close it.