Package Kit: re-use downloads from unfinished transactions

There are three parts to this change:
- In FetchFileJob, if the request fails with a timeout or IO error
  (probably because of unstable connection) attempt to resume the
  download with a range request. No limit on number of retries
  currently, maybe we should add one.
- In PackageManager, before downloading a file, look around in other
  transaction directories in case it's already there. Partial and
  complete downloads are differentiated by an attribute which the
  fetch file job maintains. For complete downloads, no fetch job is
  scheduled, for partial downloads, the fetch job will request the
  remainder of the file.
- In BHttpRequest, the implementation of SetRangeStart() and
  SetRangeEnd() have been added, along with some refactoring to
  handle listener notifications consistently. This also fixed a
  bug where the final notification for download progress was not
  emitted for compressed data.

Fixes #12414.

Change-Id: I3e285741ed0e5651594a7c2e1c7170644a9d297d
Reviewed-on: https://review.haiku-os.org/c/haiku/+/3404
Reviewed-by: Stephan Aßmus <[email protected]>
Reviewed-by: Alex von Gluck IV <[email protected]>

headers/os/net/HttpRequest.h

@@ -1,5 +1,5 @@
 /*
- * Copyright 2010-2013 Haiku Inc. All rights reserved.
+ * Copyright 2010-2021 Haiku Inc. All rights reserved.
  * Distributed under the terms of the MIT License.
  */
 #ifndef _B_URL_PROTOCOL_HTTP_H_
@@ -95,6 +95,11 @@ private:
 	// Utility methods
 			bool				_IsDefaultPort();
 
+	// Listener notification
+			void				_NotifyDataReceived(const char* data,
+									off_t pos, ssize_t length,
+									off_t bytesReceived, ssize_t bytesTotal);
+
 private:
 			bool				fSSL;