feat(cli): keep a log journal on disk with file headers and an upload limit

ctrld keeps a second log file, ctrld-journal.log, next to ctrld.log. The
journal holds all warnings and errors and each event with the field
journal=true. It stays on disk after a start of the service and after a
self-upgrade. Each log file starts with a Log header line. Each log send
upload starts with the same line, made at send time, and has a limit of
about 16 MB.

cmd/cli/cli.go

@@ -49,7 +49,6 @@ const selfCheckInternalTestDomain = "ctrld" + loopTestDomain
 const (
 	windowsForwardersFilename = ".forwarders.txt"
 	oldBinSuffix              = "_previous"
-	oldLogSuffix              = ".1"
 	msgExit                   = "$$EXIT$$"
 )
 
@@ -1497,6 +1496,8 @@ func fieldErrorMsg(fe validator.FieldError) string {
 		return fmt.Sprintf("minimum len: %q", fe.Param())
 	case "gte":
 		return fmt.Sprintf("must be greater than or equal to: %s", fe.Param())
+	case "lte":
+		return fmt.Sprintf("must be less than or equal to: %s", fe.Param())
 	case "cidr":
 		return fmt.Sprintf("invalid value: %s", fe.Value())
 	case "required_unless", "required":