cmd/ursrv, lib/ur: Collect and present encryption usage (#7448)

lib/ur/contract/contract.go

@@ -129,6 +129,7 @@ type Report struct {
 		BlockPullOrder          map[string]int `json:"blockPullOrder,omitempty" since:"3"`
 		CopyRangeMethod         map[string]int `json:"copyRangeMethod,omitempty" since:"3"`
 		CaseSensitiveFS         int            `json:"caseSensitiveFS,omitempty" since:"3"`
+		ReceiveEncrypted        int            `json:"receiveencrypted,omitempty" since:"3"`
 	} `json:"folderUsesV3,omitempty" since:"3"`
 
 	DeviceUsesV3 struct {

lib/ur/usage_report.go

@@ -267,6 +267,9 @@ func (s *Service) reportData(ctx context.Context, urVersion int, preview bool) (
 			if cfg.CaseSensitiveFS {
 				report.FolderUsesV3.CaseSensitiveFS++
 			}
+			if cfg.Type == config.FolderTypeReceiveEncrypted {
+				report.FolderUsesV3.ReceiveEncrypted++
+			}
 		}
 		sort.Ints(report.FolderUsesV3.FsWatcherDelays)