[wb1812.4.delete] Delete the custom identifier generation API (#2398)

## Summary:
This deletes the components and hooks that we had for generating hydration-safe identifiers. We are now using the built-in `useId` hook internally, and expect our consumers to do the same (or the `Id` component we provide for more complex cases).

This should not be released until the following PRs are merged and deployed to webapp:
 - Khan/webapp#28161
 - Khan/webapp#28156

Issue: WB-1812

## Test plan:
`yarn test`
`yarn typecheck`

Author: somewhatabstract

Reviewers: beaesguerra

Required Reviewers:

Approved By: beaesguerra

Checks: ✅ Chromatic - Get results on regular PRs (ubuntu-latest, 20.x), ✅ Lint / Lint (ubuntu-latest, 20.x), ✅ Test / Test (ubuntu-latest, 20.x, 2/2), ✅ Test / Test (ubuntu-latest, 20.x, 1/2), ✅ Check build sizes (ubuntu-latest, 20.x), ✅ Chromatic - Build on regular PRs / chromatic (ubuntu-latest, 20.x), ✅ Publish npm snapshot (ubuntu-latest, 20.x), ⏭️  Chromatic - Skip on Release PR (changesets), ✅ Prime node_modules cache for primary configuration (ubuntu-latest, 20.x), ✅ Check for .changeset entries for all changed files (ubuntu-latest, 20.x), ✅ gerald, ✅ Chromatic - Get results on regular PRs (ubuntu-latest, 20.x), ✅ Lint / Lint (ubuntu-latest, 20.x), ✅ Test / Test (ubuntu-latest, 20.x, 2/2), ✅ Test / Test (ubuntu-latest, 20.x, 1/2), ✅ Check build sizes (ubuntu-latest, 20.x), ✅ Chromatic - Build on regular PRs / chromatic (ubuntu-latest, 20.x), ⏭️  Chromatic - Skip on Release PR (changesets), ⏹️  [cancelled] Chromatic - Get results on regular PRs, ✅ Publish npm snapshot (ubuntu-latest, 20.x), ✅ Prime node_modules cache for primary configuration (ubuntu-latest, 20.x), ✅ gerald, ✅ Check for .changeset entries for all changed files (ubuntu-latest, 20.x), ✅ Lint / Lint (ubuntu-latest, 20.x), ✅ Test / Test (ubuntu-latest, 20.x, 2/2), ✅ Test / Test (ubuntu-latest, 20.x, 1/2), ✅ Check build sizes (ubuntu-latest, 20.x), ⏹️  [cancelled] Chromatic - Build on regular PRs / chromatic (ubuntu-latest, 20.x), ✅ Publish npm snapshot (ubuntu-latest, 20.x), ⏭️  Chromatic - Skip on Release PR (changesets), ⌛ undefined

Pull Request URL: #2398

.changeset/lemon-seals-buy.md

@@ -0,0 +1,5 @@
+---
+"@khanacademy/wonder-blocks-core": major
+---
+
+Delete the custom identifier generation API