Support for multiple .On( .. ) for two unique indexes case

[AnthonyBreneliereMedhub]

I don't find a way to use Flexlabs.Upsert in my case.

I have two unique indexes:
( CompanyId, InternalCode )
( CompanyId, Cip13)

The following command would suit my case, but two On(..) are not supported

await _context.Set<ProductInfoForCompany>()
    .UpsertRange(companyProducts)
    .On(cp => new { cp.InternalCode, cp.CompanyId })
    .On(cp => new { cp.Cip13, cp.CompanyId })
    .WhenMatched(cp => new ProductInfoForCompany
    {
        InternalCode = cp.InternalCode,
        CompanyId = cp.CompanyId,
        Cip13 = cp.Cip13,
        UpdatedAt = DateTime.UtcNow,
    })
    .WithFallbackExpressionCompiler()
    .RunAsync(ct);

With a single On ( .On(cp => new { cp.Cip13, cp.CompanyId }) is missing),

• if InternalCode has changed, (Cip13, CompanyId ) is not matched. It will then try to insert, and create a duplicate key for (Cip13, CompanyId ).
• if Cip13 has changed, (InternalCode, CompanyId ) is not matched. It will then try to insert, and create a duplicate key for (InternalCode, CompanyId ).

[Stepami]

@AnthonyBreneliereMedhub How would resulting SQL look like?

I think the issue intersects with #179