Create upgrade process for Calendar portlet in order to remove dependencies on MBMessage

• Type: Story
• Status: Closed
• Resolution: Inactive
• Affects Version/s: None
• Fix Version/s: None
• Component/s: Calendar, Calendar > Upgrade, Comments, ~ [Archived] Collaboration, ~[Archived] UI Taglibs
• Labels: None
• Epic/Theme:
  • LPS-49801

The direct use of message board classes in the calendar importing process is blocking the modularization of comments. These classes should not be used anymore in the calendar. See LPS-49801.