[CLI] `flexmeasures show beliefs` entity path in case of duplicated sensors

[victorgarcia98]

Description

The command flexmeasures show beliefs adds the sensor ID in case of trying to export sensors with the same name. However, if we want to hand this over to a third-party, it would be nicer if it included the asset names or its ancestry.

This PR changes the appended sensor ID to a string representing the "path" of the entity.

Related Items

Closes https://github.com/FlexMeasures/flexmeasures/issues/1023

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• [X] I agree to contribute to the project under Apache 2 License.
• [X] To the best of my knowledge, the proposed patch is not based on code under GPL or other license that is incompatible with FlexMeasures