Please add support for more than one search index fields for two different embedding models

[cforce]

https://github.com/Azure-Samples/azure-search-openai-demo/releases/tag/2025-05-08
"The code now has a variable for the embedding column field, so it should be possible to have a search index with fields for two different embedding models."

To allow downwards compatibility you shaall wllo to have an array (comman separated list) of fields to be used in order until a column is found with a value seit in the field (from left to right)