Usage of new Npgsql features

[gfoidl]

Npgsql offers some new features that should be considered in Marten / evaluated for use in Marten.

Parameters w/ positional placeholders

See Positional and named placeholders.

Area: perf-optimization, as Npgsql doesn't need to rebuild the SQL to substitute the named parameters with the PostgreSQL expected positional ones.

Available since Npgsql 6.

Batch API

Cf. #2424 and Raw SQL mode and new batching API

Area: perf-optimization

DbDataSource and NpgsqlDataSourceBuilder

See DbDataSource.
Accept a DbDataSource in StoreOptions.Connection(), and use that for creating the connections instead of the connection-string.

Area: usability

This would also be useful for hosted scenarios, e.g. Azure PostgreSQL flexible server, where authentication is done via "Managed Identities" and the access-token needs to be refreshed.

For reference: #2550 mentions that point too.

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PS: I'd like to contribute to these improvements (at the moment I'm quite busy, but starting with next year I think to have to time in order to dive into this)

[jeremydmiller]

Subsuming this into #2887

@gfoidl Can you follow into that issue and chime in? @oskardudycz did the work to move us to DbDataSource

[gfoidl]

@jeremydmiller sure, thanks for moving this forward. I try (and like) to help where I can.

Side note: ATM I'm working on a larger project with Marten 6.x, and when things in that project stabilize I'll give Marten 7-prereleases a try to see how it goes in production.