Use --errors-file for more than just CSV conversion errors in `influx write`

[danxmoran]

Proposal: influx write should support recording more than just CSV->LP conversion errors.

Current behavior: Only CSV->LP conversion errors are written to the location pointed to by --errors-file. Other errors are printed to console, but not persisted to file.

Desired behavior: All errors encountered during writes are written to the errors-file, along with the source line that caused the problem.

Use case: Help support efficiently debug & fix up bad lines during bulk data migrations