(core) Add sign-up and sharing/invite telemetry

Summary:
Enhances sign-up telemetry with login and verification method metadata, and
adds UTM parameters to SendGrid invite email links and Grist document links.

Test Plan: Server and manual.

Reviewers: dsagal

Reviewed By: dsagal

Subscribers: dsagal

Differential Revision: https://phab.getgrist.com/D4169

app/client/components/DetailView.js

@@ -311,6 +311,8 @@ DetailView.prototype.buildFieldDom = function(field, row) {
       kd.toggleClass('scissors', isCopyActive),
       kd.toggleClass('record-add', row._isAddRow),
       dom.autoDispose(isCopyActive),
+      // Optional icon. Currently only use to show formula icon.
+      dom('div.field-icon'),
       fieldBuilder.buildDomWithCursor(row, isCellActive, isCellSelected)
     )
   );