frontend mixpanel calls now hit dashboard

[Israellund]

Link to Issue

Closes: #10064

Description of Changes

• Frontend Mixpanel calls now hit the Mixpanel dashboard

"How We Fixed It"

-Changed code to look for process.env.APP_ENV === 'local' and changed error messages to reflect frontend and backend inits

NOTE: The original error shown in the ticket, "Failed to track event, Cannot read properties of 'undefined'" came from the code looking for process.env.APP_ENV === 'development' within the init function, and since the env var isn't 'development' anymore it was throwing that error. If you review this PR and you're seeing an error of Bad HTTP status: 0 that is most likely because an ad blocker you have is blocking the frontend mixpanel calls. Try disabling any ad blockers and trying again.

Test Plan

• Click around locally and try to trigger some of the frontend mixpanel calls found in shared/analytics.types.ts
• confirm that you see the event on the Mixpanel Dev dashboard (If you need access to Mixpanel or if you'd like for me to confirm the events in real time while you're testing just let me know.)