This PR adds the ability to subscribe to messages over a websocket.
To prevent polling data, the server can now push messages through the websocket, so the client can instantly update when new data is available.
The change is backwards compatible, still serving the status updates over the socket. If the client is providing the authentication token, it is auto-subscried to the legacy status message.
If the client is using the new authentication message, it needs to subscribe to get the status updates (and any other services it needs).
The event system has been extended to support new, and more accurate, events. This is the first step towards removing the general status update and the long-poll mechanism.
This also re-introduces the blocking marker, so the client can know if the operation is halted due to too many pending transfers.
Some endpoints have been moved to service implementations, to allow serving the exact same data from both endpoints and websocket.
This PR also updates the way the progress is handled, so that all transfers are returned to the client, and the transfer speeds for each transfer is calculated based on a small sample buffer, so the values are more accurate even if the program is paused during transfers.
This change now flushes all pending messages from the backendmanager to the database, even if the main operation crashes (or is stopped).
This ensures that the database and remote storage are more in sync.
Also removed a redundant warning from the backendmanager during shutdown, and simplified a check for active operations.
This fixes#6200
While investigating issue [#6103](https://github.com/duplicati/duplicati/issues/6103), found that connections were not disposed due to the backend pool in BackendManager's handler. Set up a FileZilla server to test the issue before and after the change, confirming that connections now close as expected with this fix.
* 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