Add custom datasets to Sycophancy

[nizamovtimur]

AS IS: attack model based only on client description
TO BE: attack model can transform initial prompts

[vortex-hue]

Hello, please can I get assigned to this, I'd like to work on this week or next please.

[nizamovtimur]

Hello, please can I get assigned to this, I'd like to work on this week or next please.

Hello! Yes, of course! I'm waiting your PR. Thanks!