userfriendly error handling of csv import

Registered by Ferdinand

currently an error causes csv import to abandon and rollback.

Suggestion
optionally - import only the valid data and create an error.csv file with broken records.

this would speed up migration processes greatly because users will only have to deal and fix broken data and must not handle valid data (and introduce other errors doing so).

Blueprint information

Status:
Not started
Approver:
None
Priority:
Undefined
Drafter:
None
Direction:
Needs approval
Assignee:
None
Definition:
New
Series goal:
None
Implementation:
Unknown
Milestone target:
None

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