Add integration tests for EditorDocument class

By integration tests we need to check that all calls are being propagated into child entities through the whole model

All checks should be done by assertion on `serialized` method of EditorDocument

| Method | Comment |
| --- | --- |
| constructor | check that the whole model is initialized with data passed to constructor |
| addBlock | check that block is created and initialized with data passed to the method |
| updateValue | check that value of related ValueNode is updated |
| updateTuneData | check if related BlockTune value is updated |
| insertText | check that related TextNode value is updated |
| removeText | check that related TextNode value is updated |
| format | check that related TextNode value is updated |
| unformat | check that related TextNode value is updated |

Final test case should assert on "real-life" scenario like adding/removing some blocks and updating their nodes