Posibility to exclude specific fields when fetching `fields: ['*']`

[timroes]

Kibana currently offers a possibility to filter out fields for spcific index patterns:

To make this working with the new fields API (which we query using fields: ['*']) it would be nice to have a way to exclude fields from there, analog to the _source.excludes parameter for _source retrieval.

This API should also support wildcards in the fields names (same as _source.excludes).

Working with nested fields

Once #67432 is merged the fields API has a specific behavior for nested fields. I would expect this exclusion API not to break it, but still return nested JSON, just without the specified exclusion keys.

For clarification a couple of (pseudo examples), given the following document:

{
  name: 'Christoph Büscher',
  addresses: [{ // <-- this is the nested field
     street: 'Fakestreet 123',
     city: 'Berlin'
  }]
}

I would assume the following things being returned from the API given those requests (simplified, and the exclusion API is totally made up):

> fields: *; fields_excluded: ['name']
{
  addresses: [{
     street: 'Fakestreet 123',
     city: 'Berlin'
  }]
}

> fields: *; fields_excluded: ['addresses.city']
{
  name: 'Christoph Büscher',
  addresses: [{
     street: 'Fakestreet 123',
     // Notice how this is stil structured, but the city is now missing
  }]
}

> fields: *; fields_excluded: ['addresses']
{
  name: 'Christoph Büscher'
}

[elasticmachine]

Pinging @elastic/es-search (Team:Search)

[timroes]

We've discussed this offline and decided, that we don't want to add a field exclusion method to the API to keep it simpler. And instead the API will continue to offer only an "inclusion" mode.