Create a buffer for text edition

[leandroBorgesFerreira]

The state flow with all stories is being updated with every new character typed. A buffer that controls when to update the StateFlow would be a good performance improvement.

[leandroBorgesFerreira]

The logic to follow is more or less this:

private fun updateTexts(stepMap: Map<Int, StoryStep>): Map<Int, StoryStep> {
        val mutableSteps = stepMap.toMutableMap()

        textChanges.forEach { (position, text) ->
            val editStep = mutableSteps[position]

            editStep?.copy(text = text)?.let { step ->
                mutableSteps[position] = step
            }
        }

        textChanges.clear()

        return mutableSteps
    }

The method updateText should be called when X new characters were added or when a action that changes the state of the Document is done (ex: checking an item, deleting an item, undoing an action)