Candle implementation is duplicated in an unclear way

It seems like there are two versions of the translation of the Candle kernel into CakeML under `candle/standard` and `candle/prover`. This is confusing: there should only be one version, or the reason for the duplication should be much more clearly documented.

Compare the Candle translations under `candle/standard` and `candle/prover` to establish whether they are genuinely duplicated and why both exist. The work is done when one implementation is removed or the distinction and reason for maintaining both are clearly documented in the relevant project location.

Written by the indexing model from the issue text.