Enable custom configuration of NpgsqlDataSourceBuilder when using AddEventuousPostgres

[gius]

Is your feature request related to a problem? Please describe.
When using PostgreSQL projectors along with NodaTime, one needs to configure NpgsqlDataSourceBuilder. However, when initializing Postgres using AddEventuousPostgres, there is no way to customize the initialization. We could manually register NpgsqlDataSource, but that would require to repeat all the additional setup that is done by AddEventuousPostgres.

Describe the solution you'd like
Add a way to access NpgsqlDataSourceBuilder created by AddNpgsqlDataSourceCore.

For example, with EF, you can configure the builder as follows:

services.AddDbContext<PostregressDbContext>((provider, options) =>
{
    options.UseNpgsql(connectionString.Value, b => b.UseNodaTime());
});

Describe alternatives you've considered
Manually registering NpgsqlDataSource.

Additional context
NodaTime + PostgreSQL

[gius]

A workaround is to configure the mappings globally. However, the function is Obsolete.

NpgsqlConnection.GlobalTypeMapper.UseNodaTime();