Change the IConfigurator Extension Methods to all return IConfigurator.

[wm-jacobo]

Is your feature request related to a problem? Please describe.
I would love it if the fluent IConfigurator extension methods such as AddExample, and other all returned IConfigurator rather than void so that they can be properly chained.

Describe the solution you'd like
I would like the extension methods as described above to have a return type of IConfigurator, and just return the IConfigurator parameter when the method is complete.

Describe alternatives you've considered
I don't really have an alternative for this. Or more accurately, the alternative is what is existing, but it is not ideal, or clean for coding.

Additional context
Add any other context or screenshots about the feature request here.

---

Please upvote 👍 this issue if you are interested in it.

[ablanchet]

If this issue still needs to be addressed I can take care of it.

Actually I fixed it on my fork, but I'm commenting here because the PR form tells me that I need to

have commented on the issue above and discussed the intended changes
A maintainer has signed off on the changes and the issue was assigned to me

---

The fix I did is available here ablanchet@d9dbab1 .
Only a few IConfigurator APIs (in both interface declaration and extension methods) were returning void.

The testing was trickier, instead of adding additional tests I figured I should instead try to use the configurator fluent API as much as possible in existing tests. This way the tests are more consistent, they give a better example on how the fluent API can be used, and it makes sure the fluent API actually works.
I have made theses changes to the tests in a separate commit: ablanchet@9f7b809 in case we want to test it in another way.

Let me know if you're ok with the solution so I can go ahead and open a proper PR.

Cheers.

[byte2pixel]

Per discussion: #1713 (reply in thread)
I will open a PR for this.