Split the Elsa.Persistence.Dapper project into multiple projects

Hi,

First of all, thank you so much for bring .NET ecosystem such a great open source workflow solution.

I'm integrating the Elsa + Dapper + Oracle to my existing project, I found current nuget package `Elsa.Persistence.Dapper` (v3.6.0) brings lots of dependencies into my project, and glad to see you had fixed it https://github.com/elsa-workflows/elsa-extensions/pull/113.

But it still has Npgsql, Sqlite, SqlServer dependencies. I think the `Elsa.Persistence.Dapper` project should be splitted into several projects, just like `Elsa.Persistence.EFCore`:
- Elsa.Persistence.Dapper
- Elsa.Persistence.Dapper.Sqlite
- Elsa.Persistence.Dapper.SqlServer
- Elsa.Persistence.Dapper.Npgsql

So that the `Elsa.Persistence.Dapper` project only keep these dependencies.
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