Gas estimation and displaying them

[0xVenky]

Description
We would like to reintroduce gas estimation in Swapr.

Definition of done

• Description is created (Task creator)
• Code is complete (Developer)
• Scope of test and what was done section is defined in task (Developer)
• Review passed (Code reviewer)
• Verified manually (QA)
• Test cases created/updated if necessary (QA)
• Change successfully merged
• Release notes added if needed

Proposal
As a user, I would like to see which dexes / aggregators cost how much gas before I place a swap. The gas costs should be converted to USD and should be added to the total cost for a swap and then sorted based on cheapest to expensive.

Additional context
1inch swaps are found to be cheaper than performing swaps with UniV3, but seems like we show UniV3 has better swap rate than 1inch because we do not calculate the gas Fees into account.