Sprint goals

• Prepare Lisk SDK v6.0.0 for beta #7210
  • #7311, #7299, #7297, #7291, #7279, #7276, #7258, #7185, #7156, #7140, #7047, #6710, #6201, #7309
• Introduce chain connector plugin #6918
  • #7224, #7223, #7222, #7221, #7220, #7219, #7218, #7217
• Update modules with events and error handlings #7211
  • #7301