Add OT for OpSetParagraphStyle

This overrides #557, and takes advantage of the newly agreed-upon and landed operation specs to have even simpler OT for `SetParagraphStyle`.

Transformations are added against the remaining operations: `InsertText`, `RemoveText`, and `SetParagraphStyle`.

The OT matrix should now have no 'gaps'. :)

The collaborative editor gets the new features: Indentation, paragraph alignment, style setting.