New swagger generation

[lcaouen]

I have found a better way to add the open-api documentation to the phoebus documentation
With the old way, the service had to be running in a CI to get the swagger.json and then possibly added to the documentation
#3124

With this pull request, the swagger.json is generated in the mvn compilation thanks to the plugin https://kbuntrock.github.io/openapi-maven-plugin.
I have also added an extension to sphinx to ignore the open-api documentation if the swagger.json is missing.
Everything can now be done locally.

Tested manually by @lcaouen and @minijackson

[jacomago]

Very nice, any possibility you could do something similar in ChannelFinder?

[georgweiss]

Maybe I am missing something in regards to how this is supposed to work. After running the doc build, I cannot find anything swagger related in the generated output. Maybe I am looking in the wrong place.

[lcaouen]

This PR concerns only phoebus\services\alarm-logger
A new plugin openapi-maven-plugin has been added to the pom.xml
This plugin will generate spec-open-api.json in the target subdirectory
This json is then used by services\alarm-logger\doc\index.rst where there is a directive .. safe_openapi:: ../../../../../services/alarm-logger/target/spec-open-api.json at the end fo the file
If the file is not found, the doc will display a message that the file is missing otherwise the swagger is displayed

[georgweiss]

Thanks @lcaouen for the clarification. Looks good, nice way of consuming open API annotations. I will use this for save-and-restore...