[Java][Feign] Add http status to feign result

[hugo-ma-alves]

To improve the previous PR #10507.

This PR adds the Http status code to the feign response.

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[wing328]

@hugo-ma-alves can we make HttpResponse look more like ApiResponse ?

The goal is to make it consistent across different Java http library.

(in other words, I suggest we rename HttpResponse to ApiResponse)

[hugo-ma-alves]

Thanks for the suggestion.
I refactored the templates to rename the HttpResponse to ApiResponse, and to keep it coherent I also renamed the JacksonResponseDecoder to ApiResponseDecoder.

[hugo-ma-alves]

I noticed that the jersey2 sample is not compiling in circleCi.

Not sure if it is related with this PR, i believe I haven't changed anything that could impact jersey2 generator.
It looks that there is an import missing in the jersey2/pojo.mustache?

I checked the history but I don't see any recent change either on the pojo.mustache or the JSON.mustache. But there was a recent rollback related with the jersey 2 generator. I did a quick test by adding the missing import and re-generated the samples. If you want you can take a look or merge it if it is ok https://github.com/hugo-ma-alves/openapi-generator/tree/bugfix/missing-jersey2-import

Just had to update my branch with the latest master changes 🤷‍♂️

[wing328]

LGTM