feat(telemetry): add Sentry to client

[caugner]

Summary

Problem

We don't get notified if users experience JavaScript errors on MDN.

Solution

Add Sentry to the client to capture client-side errors.

---

How did you test this change?

[caugner]

Unfortunately, the impact on the bundle size is significant:

File sizes after gzip:

  431 kB (-122 B)        build/static/js/482.af0cba79.chunk.js
  193.29 kB (+23.87 kB)  build/static/js/main.bd4ced2a.js
  54.45 kB               build/static/js/891.1c7c7b29.chunk.js
  28.43 kB               build/static/css/main.a0901006.css
  26.26 kB               build/static/js/966.3f90d3e3.chunk.js
  11.01 kB               build/static/js/473.20ef9fe8.chunk.js
  7.13 kB                build/static/js/400.125d8f63.chunk.js
  6.75 kB                build/static/js/768.3f1ecf1b.chunk.js
  6.3 kB                 build/static/js/68.bd5e344e.chunk.js
  5.88 kB                build/static/js/browser-compatibility-table.7ba9c730.chunk.js
  5.47 kB                build/static/js/693.d6326b63.chunk.js
  5.18 kB                build/static/js/996.bf624561.chunk.js
  4.66 kB                build/static/js/606.2ecb94c2.chunk.js
  4.29 kB                build/static/js/69.d07492fb.chunk.js
  4.12 kB                build/static/js/211.c7d57a96.chunk.js
  4.11 kB                build/static/js/863.8caec159.chunk.js
  3.57 kB                build/static/js/57.8b5ef573.chunk.js
  3.48 kB                build/static/js/717.fae76663.chunk.js
  3.11 kB                build/static/js/662.0d1c5c1b.chunk.js
  2.02 kB                build/static/css/400.46f1bacf.chunk.css
  1.88 kB                build/static/js/791.c4a8d43f.chunk.js
  1.55 kB                build/static/css/473.0d5e2f6d.chunk.css
  1.45 kB                build/static/css/606.82f4e2d2.chunk.css
  1.32 kB                build/static/css/57.57c96ebf.chunk.css
  1.15 kB                build/static/css/518.614dbbf1.chunk.css
  846 B                  build/static/js/979.80842b35.chunk.js
  817 B                  build/static/js/287.236c750d.chunk.js
  814 B                  build/static/js/507.a20b1659.chunk.js
  721 B                  build/static/css/693.90ea2bbb.chunk.css
  654 B                  build/static/css/996.feade3fe.chunk.css
  621 B                  build/static/css/768.32df508f.chunk.css
  560 B                  build/static/js/419.1bff5d09.chunk.js
  526 B                  build/static/css/211.02c1c08f.chunk.css
  296 B                  build/static/css/662.631950ad.chunk.css
  196 B                  build/static/css/419.794c818f.chunk.css
  186 B                  build/static/js/518.a5b6aabb.chunk.js
  145 B                  build/static/css/979.7bf6dfc6.chunk.css
  132 B                  build/static/css/507.933c43f0.chunk.css

On the other hand, the total size of an MDN page is about 1.1 MB, so 24 kB is not that much.

[github-actions[bot]]

This pull request has merge conflicts that must be resolved before it can be merged.