Properly implement Constructor Injection for the DI pattern

[robertmclaws]

Currently, the product passes around IServiceContainers between classes and grabs whatever it needs whenever it needs it.

However, in order for the Restier architecture to be clean and thoroughly testable, it needs to properly implement Constructor-based Dependency Injection across the entire product surface. This will require a major refactor of the application, which is not likely to happen in the 1.0 timeframe. However, some things can be done in the interim to smooth the transition to that architecture.

[jspuij]

Hi @robertmclaws. I've created a pull request for a first series of fixes that addresses this issue. It's PR #645. I've come across a lot of other issues that need a bit more discussion. I did not want to pollute the issues in this repository, so for now these issues are here:

https://github.com/jspuij/restier/issues

If you want me to move those issues over, I will. If you want to discuss them on something like Slack or Teams, i'll wait till that is set up.

The amount of classes that include a reference to Microsoft.Extensions.DependencyInjection have been reduced from 37 to 25. All classes that remain are either unit tests, or part of discussion about the design.

[robertmclaws]

I think we've gotten as far as we can in this release, so I'm going to go ahead and close this issue. If you think there is anything from your fix branch that needs to make it in before RTM, please let me know and we can talk about it.

Thanks!