This changeset uses the directory name of the SWAGGER_JSON file to use
as a root for all the files that have the following {json,yml,yaml}
extension.

By doing this one can use a docker-compose.yml like so:

environment:
- "SWAGGER_JSON=/openapi/foo.yaml"
volumes:
- "./openapi:/openapi"

or run docker like described in the installation.md file:

docker run -p 80:8080 \
-e SWAGGER_JSON=/foo/swagger.json -v /bar:/foo swaggerapi/swagger-ui

Everything from /bar is mounted in /foo and /foo is than used by nginx
to serve it's openapi specification files.

Fixes: #5318, #5496, #4915

How Has This Been Tested?

I manually tested my changes by running docker-compose with the configuration described above and manually by running docker run -p 8081:8080 -e "SWAGGER_JSON=/app/zd.yaml" -v $(pwd)/openapi:/app swaggerapi/swagger-ui

Checklist

My PR contains...

• No code changes (src/ is unmodified: changes to documentation, CI, metadata, etc.)
• Dependency changes (any modification to dependencies in package.json)
• Bug fixes (non-breaking change which fixes an issue)
• Improvements (misc. changes to existing features)
• Features (non-breaking change which adds functionality)

My changes...

• are breaking changes to a public API (config options, System API, major UI change, etc).
• are breaking changes to a private API (Redux, component props, utility functions, etc.).
• are breaking changes to a developer API (npm script behavior changes, new dev system dependencies, etc).
• are not breaking changes.

Documentation

• My changes do not require a change to the project documentation.
• My changes require a change to the project documentation.
• If yes to above: I have updated the documentation accordingly.

Automated tests

• My changes can not or do not need to be tested.
• My changes can and should be tested by unit and/or integration tests.
• If yes to above: I have added tests to cover my changes.
• If yes to above: I have taken care to cover edge cases in my tests.
• All new and existing tests passed.