Warn if node seems to duplicate another existing node

[keyserj]

Is your feature request related to a problem? Please describe. We should be able to help reduce duplication by suggesting if a node's content seems very similar to another node. This seems particularly useful for identifying duplicate claims that have been made in two different spots, because this could indicate that the claim should be extracted into some reused node in the problem mapping - perhaps a solution component, or an effect.

Describe the solution you'd like Probably add an indicator if another similar node exists. Clicking could list the similar node(s), and clicking those could take you to them

Describe alternatives you've considered

Additional context

Technical ideas Analyze the semantic similarity of nodes?

[keyserj]

related #381