Add precision to time, datetime, and timestamp field types

[ankane]

This updates Result#field_types to return the precision for time, datetime, and timestamp fields (like other types).

https://dev.mysql.com/doc/refman/8.4/en/fractional-seconds.html

Edit: Updated to only add the precision if not the default (for slightly more backwards compatibility)

[sodabrew]

I like this, but would need to put it into a major-ish release

[ankane]

Makes sense. I think it should probably always include the precision in that case.

[sodabrew]

Makes sense. I think it should probably always include the precision in that case.

Off the cuff, yes, ish? I think so.