HIP-1 [DG] Update price_band and price_ceiling

Category: Dev Grants

Summary: Improve usability of price_band and price_ceiling parameters in PMM, which is helpful for market making in volatile markets.

Linked HGP: https://snapshot.org/#/hbot.eth/proposal/0xd0c5b54badfd631d7433da0f76795a9dc0d82fc66596d547cda2f3537f903e3f

Description: See https://github.com/hummingbot/hummingbot/issues/5142

HBOT amount: I estimate that this task should take no more than 3 developer days, so I propose that the Foundation distribute 60,000 HBOT to a developer who gets a PRP merged with this change.