Add command to show available secondary indexes

[glookka]

Proposal:

Secondary indexes that are built over json attributes do json flattening and type auto-detection. However, currently there's no way to see the flattened attributes and their types. We need to add some command like SHOW TABLE <name> INDEXES that will display available secondary indexes, their types and whether they are enabled or disabled by updates.

Checklist:

^{To be completed by the assignee. Check off tasks that have been completed or are not applicable.}

- [ ] Implementation completed - [ ] Tests developed - [ ] Documentation updated - [ ] Documentation reviewed - [ ] Changelog updated - [x] OpenAPI YAML updated and issue created to rebuild clients

[sanikolaev]

LIKE also makes sense since the list may be long due to json secondary indexes.