Integrate dotnet format check into GH pipeline

[michalJakubis]

Motivation

Although we already require execution of dotnet format as one of the steps to successful contribution we do not verify that contributors have actually executed the formatting command before submitting to the repository. As a result, effective automation became impossible, as those using the dotnet format would see changes to files that were not touched by themselves during implementation.

Therefore, this PR adds dotnet format check directly to the pipeline.

Checklist

• Code follows coding conventions held in this repo
• Automated tests have been added
• Tests are passing
• Docs have been updated (if applicable)
• Temporary settings (e.g. variables used during development and testing) have been reverted to defaults

How to test

If manual testing is required, what are the steps?

[seangwright]

Can you also add the format call changes to the VS Code tasks and update the Contributing instructions like you did in Kentico.Xperience.Lucene?

The repo template does have an examples folder, even though it is empty

[michalJakubis]

Can you also add the format call changes to the VS Code tasks and update the Contributing instructions like you did in Kentico.Xperience.Lucene?

The repo template does have an examples folder, even though it is empty

I originally considered Lucene a special exception because of the recent split into multiple projects, but now I see that the approach I had to apply to Lucene also applies to single project integrations and includes test files in formatting as well. So I ended up modifying the way we implement the dotnet format here, so that we check all files except those in the example folder.