[VS Code] Add quick chat telemetry

Problem to solve

We want to track user frequency in opening quick chat in VS Code and monitor their command usage. This data will enhance our understanding of user interaction and guide iterations with quantitative insights.

Proposal

Track the following:

References

JetBrains implementation: gitlab-org/editor-extensions/gitlab-jetbrains-plugin!988 (merged) and gitlab-org/editor-extensions/gitlab-jetbrains-plugin!976 (merged).