Module cannot index taxonomies

Problem/Motivation

The module cannot index taxonomies

Steps to reproduce

1. Go to /admin/config/search/search-api/index/azure/fields
2. Add fields > Add taxonomy term(s) (ex. field_keywords:entity:name).

Proposed resolution

Adding taxonomy terms for example field_keywords:entity:name.
If array, convert it into comma-separated string.

Remaining tasks

User interface changes

API changes

Data model changes