Map support out-of-range date/time mappings

[roji]

When interacting with date/time values which are outside the .NET types' ranges, Npgsql has some special provisions for this:

PG type	CLR type	Meaning
timestamp/timestamptz	long	Microseconds since 2000-01-01 00:00:00.000000
date	int	Days since 1/1/2000
interval	NpgsqlInterval	Months, days, microseconds in day

Make these work at the EF provider level.

[AraHaan]

Can 6.0.8 also update efcore itself to 6.0.8 as well, and then 6.0.9 update to efcore 6.0.9 too?

[roji]

@AraHaan usually we take a dependency on the latest EF Core version from EFCore.PG, but I forgot to do that in the 6.0.7 release; though you can easily just take a dependency on the latest version yourself in the application csproj.

(however that's not really relevant here, marking as off-topic)