Openapi3 upgrade

[fasblom]

Background of the PR:

• Upgrade the dependency of the swagger-ui from 2.1.4 -> 5.11.1 as the previous package is old and with security issues
• As a consequence implemented the OpenAPI 3 specification instead of OpenAPI 2

Consequences:

• Updated outdated packages
• Updated swagger.js to follow OpenAPI 3 specification
• Removed outdated fields like produces, consumes from swagger.js and swagger-html
• Updated way of generating the Swagger-HTML site based on swagger-iu

Some comments:

• The full OpenAPI 3 spec is not implemented - but the core concepts that are in line with what has been implemented as per the previous release

Resolves #83 , Resolves #82 , Resolves #74 , Resolves #51

[linux-foundation-easycla]

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[fasblom]

@knolleary - Have you had a chance to look at this PR for updating Swagger?

[knolleary]

I have not looked. I do not actively use this node, but I will try to review it soon.

I suspect changing the format of the spec it generates warrants a major version bump as it could be considered a breaking change.

[fasblom]

Major version bump sounds reasonable as it changes quite a lot given the new OpenAPI-spec. Have you had a chance to look at it yet @knolleary ? Kind regards