Add extended ElasticSearch 7+ support and more flexibility to `elastic` lib

[cewald]

Related issues

According to the changes in vue-storefront-api I've made to fully support ES7 and use the build in ES client class in this PR: vuestorefront/vue-storefront-api#512 adapted to storefront-api.

These are some proposals to have a more stable support for the current ES version and more flexibility:

• Remove type attribute from attribute/service/list method as it is already resolved by the adjustQuery depending on its version and will drop an ES exception if it is left in the search query
• Remove _updateQueryStringParameter method as it is unused as it is nowhere called
• Add getTotals method to elastic lib as from ES7 the totals return value is an object
• Add pingTimeout option and possibility for multiple ES hosts to elastic lib
• Use elasticsearch client library in catalog endpoint to make ES settings more consistent
• Localize catalog-attributes that stored in cache
• Prevent exception in redis-tag-cache when tags are empty
• Bugfix for attribute aggregations with nested buckets

These changes are pretty similar to the ones I've proposed for the vue-storefront-api: vuestorefront/vue-storefront-api/pull/512.

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