suggest: Add possibility to pass custom input block

[narqo]

Compositional controls like contacts selection or tag selection might need to use custom input implementation.

suggest should provide an ability to pass any input that satisfies current interface as a custom field in BEMJSON:

{ block : 'suggest',
  mods : { has-dataprovider : 'tags-store' },
  input : {
    block : 'input',
    ···
  }
}