Summary of the new feature / enhancement

Use case:
The supplier(s) of the csv files I need to process aren't very keen on which delimiters they use.
In most cases the delimiter of an csv file could be determined from the header and/or the first few records (especially if fields are quoted)

Proposed technical implementation details (optional)

Support an -Delimiter Auto value for Import-Csv and ConvertFrom-Csv
If the delimiter can't be determined, default to a comma (,), or if the delimiter can't be determined with certainty, return a (non-terminating) error or warning.