[#1223] lens/tui: Add alternative text on open an empty bucket

Add an alternative text to display in the selected bucket's records
view in case that bucket is empty.

Signed-off-by: Aleksey Savchuk <a.savchuk@yadro.com>

cmd/frostfs-lens/internal/tuiutil/records.go

@@ -138,6 +138,16 @@ func (v *RecordsView) Draw(screen tcell.Screen) {
 	// }
 
 	v.DrawForSubclass(screen, v)
+
+	// No records in that bucket.
+	if v.firstRecordIndex == v.lastRecordIndex {
+		tview.Print(
+			screen, "Empty Bucket", x, y+1, width,
+			tview.AlignCenter, tview.Styles.PrimaryTextColor,
+		)
+		return
+	}
+
 	for index := v.firstRecordIndex; index < v.lastRecordIndex; index++ {
 		result := v.records[index].Entry
 		text := result.String()