fix(build): use optional-require dependency

[balazsorban44]

What:

Use optional-require to require certain modules optionally.

Why:

To my sadness, after trying out #1682 on a local project, I discovered that Next.js Webpack will try to include modules in the dev/prod builds that were added through dynamic imports, **even though they are wrapped in a conditional that is never true.*. That just seem to be a limitation/behaviour I do not understand fully, to be honest. If someone visits this PR, please enlighten me 💡, or show me to some documentation/reasoning! In the meantime, let's see that using a wrapper for importing helps.

I am trying optional-require instead of require_optional first, as the latter looks to be unmaintained (with still a number of downloads/week though), and even the mondodb module (that we used as an example when implementing optional modules) switched from it, as it introduced a bug in Windows.

How:

Switch out the failed dynamic imports to optionalRequire calls, and see if solves the problem.

Checklist:

• Documentation
• Tests
• Ready to be merged
  

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[github-actions]

🎉 This PR is included in version 4.0.0-next.3 🎉

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[balazsorban44]

DISCLAIMER: Did not seem to work as expected... I will keep exploring ways that will make typeorm and nodemailer truly optional, so we can drastically reduce bundle size for those not using any of them.