fix(typing): Allows all busboy options on plugin registration

[johaven]

Checklist

• run npm run test and npm run benchmark
• tests and/or benchmarks are included
• documentation is changed or added
• commit message and code follows the Developer's Certification of Origin
  and the Code of conduct

Fix
Options like preservePath are not known

[gurgunday]

Thanks for the PR

Can you add a test using tsd?

[johaven]

Can you add a test using tsd?

done :)

[mcollina]

lgtm

[johaven]

The linter seems to be broken :/

[mcollina]

Here is a PR that fixes linting #538

[mcollina]

Can you please rebase your PR?

[mcollina]

@gurgunday ptal