v1.6.1 - modify new user and existing user update workflows

[mjstealey]

Allow users to logically merge accounts based on different IdPs and different emails to a single CoPerson record within the registry

• [x] Modify "get_person_by_login_claims" in "people_utils.py" to only search by claim sub
  • when fab_person is not found, search COmanage for sub identifier and determine whether to update and existing account, or create a new account
• [x] Modify "update_fabric_person" in "people_utils.py" to only scan for new identifiers and retain prior claim information
• [x] Add new COmanage workflow "Re-invite an existing collaborator"
  • Allow Google/Microsoft/ORCID/GitHub based accounts
  • email does not need to be the same as existing account email

[mjstealey]

merged, closing