Add Couchbase EF Core Provider Integration

[azaddhirajkumar]

Is there an existing issue for this?

• I have searched the existing issues

Is your feature request related to a problem? Please describe the problem.

ABP Framework doesn't currently support Couchbase database, which is a popular enterprise NoSQL document database.

Describe the solution you'd like

Add a new package Volo.Abp.EntityFrameworkCore.Couchbase using the official Couchbase EF Core Provider (Couchbase.EntityFrameworkCore).

Following the same pattern as Volo.Abp.EntityFrameworkCore.PostgreSql:

• AbpEntityFrameworkCoreCouchbaseModule - Module registration
• UseCouchbase() extension methods for AbpDbContextOptions and AbpDbContextConfigurationContext
• CouchbaseConnectionStringChecker - Connection validation
• AbpCouchbaseModelBuilderExtensions - Model builder extension
• Add Couchbase to EfCoreDatabaseProvider enum

Additional context

• Provider: Couchbase EFCore Provider
• NuGet: Couchbase.EntityFrameworkCore
• Compatibility: EF Core 8.0+, .NET 8+, Couchbase Server 7.6+

I'm willing to implement this and submit a PR.