This PR has a large blast radius because it takes the final step and bumps up the Controller to be fully async.
We have historically done a piece-by-piece update, so all operations were already async but the controller interface was kept synchronous.
With this update, the controller is now fully async and all tests are updated.
Most places where the new C# compiler warns about function names not ending in `Async` were also adressed, giving a massive refactor change.
Functionally, no changes are done.
* Rewrite the backend manager.
This creates a new more logic backend manager that handles all backend operations.
For each top-level operation, there is now a single backend manager instance that is passed to sub-commands.
The internals of the backend manager are now rewritten to use async logic instead of threading.
The design uses a single task runner that dispatches operations and honors concurrent settings and limits from one place.
The logic for each operation has been moved into a separate files/classes to make it easier to understand each operation.
This fixes#5804
* Fixed a few issues with not awaiting tasks
* Fixed not creating empty databases
* Fixed an issue with hashes not being recorded on download
* Reworked the download logic to avoid attempting to decrypt the file if it has been modified.
* Review fixes
* Renamed db collector to better reflect the purpose.
* Review fixes
Kenneth Skovhede