fix(common)!: drop broken support for promises on exports of modules

[micalevisk]

PR Checklist

Please check if your PR fulfills the following requirements:

• The commit message follows our guidelines: https://github.com/nestjs/nest/blob/master/CONTRIBUTING.md
• Tests for the changes have been added (for bug fixes / features)
• Docs have been added / updated (for bug fixes / features)

PR Type

What kind of change does this PR introduce?

• Bugfix
• Feature
• Code style update (formatting, local variables)
• Refactoring (no functional changes, no api changes)
• Build related changes
• CI related changes
• Other... Please describe:

What is the current behavior?

Issue Number: closes #13733

What is the new behavior?

we don't support supplying promises to the exports option of @Module()/dynamic module anymore. This feature never worked, anyway.

Does this PR introduce a breaking change?

• Yes
• No

[coveralls]

Pull Request Test Coverage Report for Build d2645ff2-1080-442a-91ba-c314def39343

Details

• 0 of 0 changed or added relevant lines in 0 files are covered.
• No unchanged relevant lines lost coverage.
• Overall coverage remained the same at 92.243%

---

Totals
Change from base Build 72f148bc-4145-44b3-a3c4-06a616307114:	0.0%
Covered Lines:	6754
Relevant Lines:	7322

---

💛 - Coveralls