Add tracking for visual studio extension

What does this MR do and why?

Add tracking for visual studio extension

This implements RedisHLL tracking for api requests made from the GitLab Visual Studio extension to GitLab.

Changelog: added

To Test:

1. bundle exec rails c
2. Ensure that the count is 0: Gitlab::UsageDataCounters::HLLRedisCounter.unique_events(event_names: 'i_editor_extensions_user_visual_studio_api_request', start_date: Date.current.beginning_of_week - 1.week, end_date: Date.current.next_week + 1.week)
3. Send an api request with the appropriate user agent: curl --request GET -H "PRIVATE-TOKEN: {TOKEN_HERE}" -H "User-Agent: gl-visual-studio-extension" "http://localhost:3000/api/v4/projects?page=1"
4. Ensure the count is now 1: Gitlab::UsageDataCounters::HLLRedisCounter.unique_events(event_names: 'i_editor_extensions_user_visual_studio_api_request', start_date: Date.current.beginning_of_week - 1.week, end_date: Date.current.next_week + 1.week)