(core) Tweak telemetry

Summary: Adjusts the level of telemetry collected from Grist SaaS.

Test Plan: Tested manually.

Reviewers: paulfitz

Reviewed By: paulfitz

Subscribers: paulfitz

Differential Revision: https://phab.getgrist.com/D3899

app/common/hashingUtils.ts

@@ -0,0 +1,12 @@
+import {createHash} from 'crypto';
+
+/**
+ * Returns a hash of `id` prefixed with the first 4 characters of `id`.
+ *
+ * Useful for situations where potentially sensitive identifiers are logged, such as
+ * doc ids (like those that have public link sharing enabled). The first 4 characters
+ * are included to assist with troubleshooting.
+ */
+export function hashId(id: string): string {
+  return `${id.slice(0, 4)}:${createHash('sha256').update(id.slice(4)).digest('base64')}`;
+}