Update setup instructions for typescript files

[joeldenning]

Summary

Typescript files require .ts or .tsx file extension. Now that babel can parse typescript with @babel/preset-typescript, we should use it.

Test plan

I tried this out locally and it worked for both typescript and js files.

[codecov-io]

Codecov Report

Merging #8624 into master will not change coverage.
The diff coverage is n/a.

@@          Coverage Diff           @@
##           master   #8624   +/-   ##
======================================
  Coverage    63.4%   63.4%           
======================================
  Files         274     274           
  Lines       11342   11342           
  Branches     2770    2770           
======================================
  Hits         7191    7191           
  Misses       3534    3534           
  Partials      617     617

---

Continue to review full report at Codecov.

Legend - Click here to learn more
Δ = absolute <relative> (impact), ø = not affected, ? = missing data
Powered by Codecov. Last update f7f787d...e7f3197. Read the comment docs.

[SimenB]

Thanks!

[github-actions]

This pull request has been automatically locked since there has not been any recent activity after it was closed. Please open a new issue for related bugs.
Please note this issue tracker is not a help forum. We recommend using StackOverflow or our discord channel for questions.