[Star tree] Star tree codec changes

[bharath-techie]

Is your feature request related to a problem? Please describe

To support creation of star tree during indexing flows, we need changes in codec to build star tree index during flush and merge flows. We also need changes to read the indexing structures to support querying star tree indices.

Describe the solution you'd like

We will enhance the DocValuesFormat to support star tree creation during flush and merge. We will initially plan to support this via custom codec. The approach will be as mentioned in #12498 (comment).

Related component

Indexing:Performance

Describe alternatives you've considered

No response

Additional context

No response

[bharath-techie]

Closing this issue as changes are merged