Allow mix of single objects and enumerables in valueset

[andrewmckaskill]

This change updates the yield helper method that converts an IDictionary<string, object> to an IDictionary<string, IEnumerable<object>>.

This allows for greater flexibility when constructing valueSets. Currently, if you have a single field that requires multiple values (say for faceting), you must use the IDictionary<string, IEnumerable<object>> overload and wrap all your fields in arrays or other enumerable structures. This change means that you can submit an array for a field and it will be automatically interpreted correctly.

Before - with all other fields wrapped in arrays:

var multiValues = new Dictionary<string, IEnumerable<object>>
{
    // this is a special field used to display the content name in the Examine dashboard
    [UmbracoExamineFieldNames.NodeNameFieldName] = new[] { content.Name! },
    // add the fields you want in the index
    ["id"] = new List<object> { content.Id },
    ["udi"] = new[] { content.GetUdi() },
    ...
    // GetTags returns an array of tags
    ["tags"] = GetTags(content)
};

After - with mix of single objects and arrays:

var indexValues = new Dictionary<string, object>
{
    // this is a special field used to display the content name in the Examine dashboard
    [UmbracoExamineFieldNames.NodeNameFieldName] = content.Name!,
    // add the fields you want in the index
    ["id"] = content.Id,
    ["udi"] = content.GetUdi(),
    ...
   // GetTags return an array of tags
    ["tags"] = GetTags(content),
};

[Shazwazza]

I like the idea. Are you able to add a unit test for this and/or integration tests in the LuceneIndexTests?

[andrewmckaskill]

I like the idea. Are you able to add a unit test for this and/or integration tests in the LuceneIndexTests?

Sure - let me take a look at it today.

[nikcio]

@andrewmckaskill This PR currently has merge conflicts could I get you to rebase or merge release/4.0 into your branch? 😄
This is properly in response to the addition of nullables in the Examine project so please use the appropriate nullable modifiers for your addition.

[andrewmckaskill]

@nikcio No it was just a simple conflict in the import statements. I've gone ahead and rebased on top of current release/4.0 branch for you to make the history clean.

The only change in this PR is the extra logic inside the Yield method to deal with Enumerables. I can't see VS complaining about any nullable items in that method, so I think it's good to go.