Optimize swagger-ui-dist loading performance

[edgesite]

PR Checklist

Please check if your PR fulfills the following requirements:

• [x] The commit message follows our guidelines: https://github.com/nestjs/nest/blob/master/CONTRIBUTING.md
• [x] Tests for the changes have been added (for bug fixes / features)
• [x] 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)
• [x] Refactoring (no functional changes, no api changes)
• [ ] Build related changes
• [ ] CI related changes
• [ ] Other... Please describe:

Does this PR introduce a breaking change?

• [ ] Yes
• [x] No

Other information

code:

const start = Date.now();
const config = new DocumentBuilder().build();
const document = SwaggerModule.createDocument(app, config);
SwaggerModule.setup('api', app, document);
console.log(`Swagger loaded in ${Date.now() - start}ms`);

before: Swagger loaded in 101ms after: Swagger loaded in 26ms see: https://github.com/swagger-api/swagger-ui/issues/4502

[kamilmysliwiec]

AFAIR swagger-ui-dist suggests to use the getAbsoluteFSPath function for this

[edgesite]

getAbsoluteFSPath function is actually a shorthand of require('absolute-path.js'), and the absolute-path.js have test, so we can concern it as stable API.

[kamilmysliwiec]

lgtm