Fix config doc annotations for OpenAPI builder

[tjquinno]

Part of #4209 (and part of #4314)

Reviewers: Please pay particular attention to the default value for the static-file config setting as proposed. Our code looks for a static OpenAPI document file at META-INF/openapi. and any of yml, yaml, or json for the file type.

I've expressed the default value for config doc purposes as META-INF/openapi.{json,yaml,yml} to try to capture this succinctly, although obviously that's not a value that a user would be able to copy and paste into an actual config file and have it work.

I think that's OK. In fact, expressing this in some other way would be more verbose and no more clear, I think.

[tjquinno]

After I created this PR, I discovered that @dalexandrov has also been working on some of the same files but had not created a PR yet (although he has subsequently: #4421). He and I will be reconciling our changes. I have marked this as a draft until he and I figure that out.

[tjquinno]

NOTE: I made a small local change to the config doc generator tool to get the proper output in the docs/shared/config/io.helidon.openapi.SEOpenAPISupport.adoc file in the latest push. I am in touch with David and Tomas to see if I was doing something wrong with the annotations or if there is, in fact, a change needed in the tool.

[tjquinno]

In a semi-private chat, Tomas pointed out that in the merging config options I was incorrectly specifying the impl builder instead of the interface as type. The latest push fixes that, and when I ran the tool locally, the merging seems to be happening as expected.