Enhance AI features telemetry

Summary

Currently only "code_suggestion_requested" event end in Rails app which makes it hard to make meaningful analytics of Code Suggestion features. We need to get more information to work with in order to measure impact of AI features on DevOps processes.

Proposal

Route following events to Rails platform (new telemetry ingestion endpoint):

1. code_suggestion_accepted, code_suggestion_rejected, code_suggestion_shown.
2. users git branch name
3. suggestion language
4. suggestion size in LoC
5. unique suggestion identifier.
6. ....anything else?

TODO

1. complete list of metrics and data
2. verify with legal