WIP: ApiExtension Decorator - solves #195

[tomchinery]

This pull request is a WIP (work in progress) to help indicate that I am actively working on this issue so contributors are not doing duplicate work.

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
[x] 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: #195

What is the new behavior?

There is a new method decorator that you can use to add an OpenAPI Extension to a path:

@ApiExtension(<extensionName>, <extensionPropertyObject>)

@ApiExtension('x-foo', { hello: 'world' })

Does this PR introduce a breaking change?

[ ] Yes
[x] No

Other information

[lock]

This thread has been automatically locked since there has not been any recent activity after it was closed. Please open a new issue for related bugs.