Update Segment identify calls to remove email, add domain

[noeldevelops]

Summary of Changes

• Instead of trying to send the full email to Segment, extract the domain ending and send that.
• Created a new function specifically for sending a Segment Identify call that handles the details of parsing user data from the Session or UserInfo object.
• Adds a call to this ^ function during the authentication part of Extension Activation to catch existing sessions.
• ⚠️ Files changed looks bigger bc I refactored to split off getTelemetryLogger from the other functions to make testing easier (since mocking module-level functions is still a challenge)

Any additional details or context that should be provided?

• We found that VS Code TelemetryLogger class will redact any email-looking string via RegEx. We'd like to filter our final analytics data by internal (Confluent) users while respecting this PII, hence the addition of a domain property instead of email
• Here's the event as it appears in Segment:

Pull request checklist

Please check if your PR fulfills the following (if applicable):

Tests

• Added new
• Updated existing
• Deleted existing

Other

• Does anything in this PR need to be mentioned in the user-facing CHANGELOG or README?
• Have you validated this change locally by packaging and installing the extension .vsix file?

  gulp clicktest

[MSeal]

Some minor questions, good for merge independently imo.

[MSeal]

I'd of maybe just done if @ present, then split and grab [1] since we don't care about other properties and expect it to always be an email entry anyway.

[noeldevelops]

does sound simpler! I wasn't sure if we were 100% certain this will be email every time. Happy to update if it makes sense to do so in follow ups

[MSeal]

Why this change?

[noeldevelops]

Just setting us up to handle logout in near future... We're already sending vscodesessionid with the common properties in data, and the segmentAnonId is stable in each instance of the TelemetryLogger, so it won't make much difference now but in updates I'll be able to reset the anon id (during log out flow or other cases where the User Id might be new for an existing VSCode session)