PostgreSQL 10 - Use BIGINT IDENTITY instead of BIGSERIAL

[to11mtm]

Creating this based on akkadotnet/Akka.Persistence.PostgreSql#69

We can do this once Linq2Db has a Postgres 10 ProviderName available, similar to how we handle SQLite's identity column rules today.

[CumpsD]

You can probably use https://github.com/linq2db/linq2db/blob/34949525d85417551f6a37b1462643b027a37918/Source/LinqToDB/ProviderName.cs#L177 ?

		/// <summary>
		/// PostgreSQL 15+ data provider.
		/// </summary>
		public const string PostgreSQL15 = "PostgreSQL.15";