Add exclusion support to response filtering

[tlrx]

This PR adds support for excluding filters to the response filtering feature.

It adds the parameters filter_path_include and filter_path_exclude that can be used to combine inclusive and/or exclusive filters when filtering the response from a REST API request execution:

GET /_cluster/state?filter_path_include=metadata.indices.*.state&filter_path_exclude=metadata.indices.logs-*

{
  "metadata" : {
    "indices" : {
      "index-1" : {
        "state" : "open"
      },
      "index-3" : {
        "state" : "open"
      },
      "index-2" : {
        "state" : "open"
      }
    }
  }
}

When both filter_path_include and filter_path_exclude are set, it works by chaining two FilteringGeneratorDelegate: one for content exclusion and one for content inclusion (it always excludes first). If the whole content is filtered out, the output is an empty object.

[javanna]

you should sync up with @elastic/es-clients to make sure that they make the same change in their clients/runners if needed. Otherwise their runners may barf as some parameters are provided although they are not listed in the api spec.

[tlrx]

I agree, but I finally removed the filter_path_excludes and filter_path_includes in favor of a +/- support using the current filter_path parameter, as Clinton suggested.

[clintongormley]

@tlrx what about ant syntax, eg

?filter_path=metadata.indices.*.state,-metadata.indices.logs-*

[tlrx]

@clintongormley Sure, I also prefer this notation.

[tlrx]

This has been updated according to your comments @clintongormley @javanna

[clintongormley]

Worth specifying which takes precedence: include or exclude

[tlrx]

I updated the doc.

[s1monw]

left some minors LGTM otherwise

[tlrx]

Thanks @s1monw - merged with your suggestions.

[s1monw]

thanks @tlrx