AutoMap/Infer TimeSpan properties by default

[russcam]

Reference to #1643

I think we should consider handling/inferring System.TimeSpan properties by default, storing it as a double representing the TotalMilliseconds of the TimeSpan. Storing it as a string makes less sense as you may want to query on the field and this would be unituitive on a string field.

Doing this would require a custom JsonConverter for TimeSpan.

What are your thoughts, @Mpdreamz, @gmarz?

[RobinRieger]

👍

Manually adding attribute for 'double' here atm, because string mapping doesn't make any sense....