[!!!][FEATURE] Add flag to enable/disable fulltext indexing per nodetype

Adds a new enable flag for full text indexing. By default anything
inheriting from TYPO3.Neos:Document will be fulltext indexed.

Breaking since the isFulltextRoot flag has been moved to a new position.

Here is how the configuration looks like now:

```
  'TYPO3.Neos:Document':
    elasticSearch:
      fulltext:
        enable: true
        isRoot: true
```