Add properties to IndexingParameters from .NET's IndexingParametersExtensions

Follow-up from #Azure/azure-sdk-for-net#12154. We want to make those changes to the `configuration` member actual model properties instead of extension methods. This will track the work to update the swagger with what the server already supports, though we may want to rename some of the client enum values depending on whether "storageMetadata" truly means "metadata" in the way Storage refers to it, which has "content", "metadata", and "properties" as separate concepts.

Ideally, all these changes are in swagger so generators just pick it up automatically.

/cc @jennifermarsman @bleroy @brjohnstmsft

Start by reviewing the changes in .NET issue #12154 and the existing IndexingParametersExtensions methods, then inspect the swagger definition for the configuration member. Done means the supported fields are represented as generated model properties and the storageMetadata enum naming is resolved against the content, metadata, and properties concepts.

Written by the indexing model from the issue text.