Improve AnalyzeExpense Support

Currently there is limited support for AnalyzeExpense in Textractor.
We support sync and async API calls.

However we need to implement the following:

- [x] Allow duplication of KV for summary fields, they are not unique and there can be multiple TOTAL fields for example
- [x] Add support for line items. Line items are typically stored in a tabular format and represent individual elements from a transaction
- [x] Add auto-complete and attribute support for each of the existing summary fields
- [x] Add visualization support for summary fields to distinguish them from the normal KV
- [x] Add a tutorial that shows the use of the analyze expense API

Start by reviewing the existing AnalyzeExpense sync and async API support in the repository. Check the issue's completed items—summary-field duplication, line items, autocomplete and attributes, visualization, and the tutorial—and identify what remains before proposing a bounded change. Done should mean the remaining AnalyzeExpense support is implemented and demonstrated.

Written by the indexing model from the issue text.