Allow passing a custom script and params if hash matches to scripted updates

[Mpdreamz]

var options = new CatalogIndexChannelOptions<HashDocument>(Client.Transport)
{
	IndexFormat = indexPrefix + "{0:yyyy.MM.dd.HH-mm-ss-fffffff}",
	ActiveSearchAlias = indexPrefix + "search",
	BulkOperationIdLookup = c => c.Id,
	ScriptedHashBulkUpsertLookup = !useScriptedHashBulkUpsert ? null : (c, channelHash) =>
	{
		var hash = HashedBulkUpdate.CreateHash(channelHash, c.Id, c.Title ?? string.Empty);
		c.Hash = hash;
		return new HashedBulkUpdate("hash", hash, "ctx._source.index_batch_date = params.index_batch_date",
			new Dictionary<string, string>
			{
				{ "index_batch_date", c.IndexBatchDate.ToString("o") }

			});
	},

In this example instead of the default noop script when the hash matches you can now specify a different script to run.

Here we update index_batch_date always but only if the hash does not match will the whole document (with e.g an update_date) be updated.

This allows us to both query for updates (update_date gte start of indexing) and delete anything that wasn't part of this upate (index_batchdate lt start of indexing).