fix: trade impact is including protocol fees for chainflip

[NeOMakinG]

Description

Chainflip price impact was wrong because amount out was excluding fees

I used a shortcut by calculating the inAmount with the rate chainflip send to us, so the price impact is nearer from the right one now

If you want to verify other price impacts, keep in mind that we do with what we have, some quotes provide great data to have an accurate price impact, some others are pretty hard to provide an accurate price impact and it's more an estimation than a precise price impact

For chainflip it's pretty close to the true now

Issue (if applicable)

closes #8514

Risk

Low

High Risk PRs Require 2 approvals

What protocols, transaction types, wallets or contract interactions might be affected by this PR?

Testing

• Try a quote for chainflip (ETH for BTC for example)
• Price impact should be around 1% instead of 12

Engineering

n/a

Operations

n/a

• 🏁 My feature is behind a flag and doesn't require operations testing (yet)

Screenshots (if applicable)

[gomesalexandre]

Math does look sane/r than before (i.e use the input/output fiat rate to calculate a pseudo amount before fees as a prorate of sorts) for smolish amounts, tested against develop (right):

Added some suggested changes re: dependency-injecting the fiat rate between sell/buy ourselves so we don't rely on upstream with market-data discrepancies which could cause issues in calculations (either being off at best, or having a negative number at worst), though happy to have that as a follow-up 🙏🏽