Make block cacheable

This patch solved our issue, where authenticated users lost the pre-configured arguments on page reload

Merge latest 2.0.x so we can have CI tests in the MR.

\Drupal\block\BlockViewBuilder::viewMultiple collects cache metadata correctly after applying the MR

Example without the patch:

"contexts" => [
  0 => "languages:language_interface"
]
"tags" => [
  0 => "block_view"
  1 => "config:block.block.front_facetsblock"
]

With the patch:

"contexts" => [
  0 => "languages:language_interface"
  1 => "languages:language_content"
  2 => "url.query_args"
  3 => "user.node_grants:view"
  4 => "facets_filter:f"
]
"tags" => [
  0 => "block_view"
  1 => "config:block.block.front_facetsblock"
  2 => "config:facets.facet.test"
  3 => "config:search_api.index.test"
  4 => "search_api_list:test"
  5 => "config:views.view.test_facets_block"
]