I would like to configure datasource including ia. field mapping for json string containing collection.
Yes you can - get the latest Azure Search SDK from nuget.org and use DataSource.AzureTableStorage method.
You no longer need to use field mappings to populate string collection fields - Azure Search will do this for you automatically as long as the strings are formatted as a JSON array of strings. However, should you need field mappings for other reasons, they are available as FieldMappings property of Indexer class.