Rename SimilarToList to SimilarToPreviousValues

[ShreyaR]

[zsimjee]

imo SimlarToList or SimilarToValues are better names than previous values (that's not a strong opinion though). When last I used the validator, it seemed unintuitive to pass prev_values as a param (stronger opinion).

What do you think of this?

1. Keep SimilarToList as the name
2. rename prev_values to comparison_list or comparison_values

[zsimjee]

closing - been a while, we have these on the hub submission https://hub.guardrailsai.com/validator/guardrails/similar_to_previous_values