OpenAPI 3: Generate valid operations/parameters

[WoH]

This PR should ensure we generate a valid spec for the GetController in the tests.

I moved the schema and example to the correct position to ensure we mostly* comply with the specification.

*There are still $refs that should be allowed in 3.1, so I don't see a reason to fix these.

[dgreene1]

@WoH there have been a lot of changes to the master branch. I can see that Github doesn't appear to see an issue, but that's because we dont (yet) have the unit tests running here. So can you please update this branch with master and then fix any breaking tests.

Additionally, would you be willing to see if this PR fixes this other open issue #389 with OpenAPI 3.0?

[WoH]

I saw that and rebased from 7f96d8d to
465113f to address the changes. (See here for example, where I resolved a merge conflict)
I'll take a look at these issues, thanks for pointing them out 👍

[WoH]

I ran the output through validation, these are 3 types of errors in the output from #389:

• Property produces is not allowed.
• Property schema is not allowed.
• Property type not allowed.

All 3 of these issues should be handled.
Maybe @luli0822 wants to run his code against this PR ;)