Remove unused stuff

[RafaelJCamara]

Description

Removed unused references, and variables.
Simplified namespaces.
Adjusts in tests, because their build was failing because of not awaiting async method calls.

Checklist

Please make sure you've completed the relevant tasks for this PR, out of the following list:

• Code compiles correctly
• Created/updated tests
• Extended the documentation

[philliphoff]

I'm personally not a fan of abbreviating namespaces in this way, even if it's technically allowed. For Dapr.Client, in particular, there's just too many other "client" types and I'd prefer to be explicit. (If anything, I would propose moving using statements to be above the namespace declaration and use the namespace <ns>; form rather than namespace <ns> { /* ... */ }. That's a significant refactor, however, so it's only been done on a piecemeal basis when working within individual files.)

[philliphoff]

While I appreciate the effort to cleanup the codebase--and there's plenty to do there--this is a hefty PR. While the changes all appear individually trivial, it would be easy to miss a change that might have unintended consequences. I would prefer to split this up into several PRs that each address a particular thing (e.g. removal of unused using statements, another that cleaned up unused fields/values, etc.) which will make the changes easier to review.

[RafaelJCamara]

While I appreciate the effort to cleanup the codebase--and there's plenty to do there--this is a hefty PR. While the changes all appear individually trivial, it would be easy to miss a change that might have unintended consequences. I would prefer to split this up into several PRs that each address a particular thing (e.g. removal of unused using statements, another that cleaned up unused fields/values, etc.) which will make the changes easier to review.

I'll split that in multiple PRs! Thank you so much for the feedback!