Track account creation from VS Code extension CTAs

Created by: jjinnii

In order to understand the effectiveness of the VS Code extension in Sourcegraph Cloud account creation (Acquisition), we want to log UTM parameters when a CTM for account creation is clicked in the VS Code extension.

A list of events for UTM parameters can be found in the UTM tracker. I've added VS Code events in lines 142-144, one for each CTA we have in the VSCE:

• Sidebar CTA
• Banner CTA
• CTAS from Save Search, and Create Monitor buttons

These UTM parameters will be used to track traffic from these CTAs to the VSCE signup page, and eventually account creation. End goal is to create a funnel conversion view with steps:

1. Clicked on CTA in VSCE
2. Landed on Cloud VS Code sign up page
3. Clicked sign up
4. Created account
5. Synced repo