Allow configuration for Application-driven index settings

App indexes, such as commerce-ml-*, search-tuning-* and workflow-metrics-* etc. use hard coded index settings ie:

• modules/dxp/apps/commerce/commerce-machine-learning-impl/src/main/resources/META-INF/search/settings.json

• modules/dxp/apps/portal-search-tuning/portal-search-tuning-rankings-web/src/main/resources/META-INF/search/liferay-search-tuning-rankings-index.json

• modules/dxp/apps/portal-search-tuning/portal-search-tuning-synonyms-web/src/main/resources/META-INF/search/liferay-search-tuning-synonyms-index.json

• modules/dxp/apps/portal-workflow/portal-workflow-metrics-service/src/main/resources/META-INF/search/settings.json

There should be a way to configure these indexes for the search app indexes which can be used as a pattern for other app indexes.