Gas estimation and displaying them

[0xVenky]

Description We would like to reintroduce gas estimation in Swapr.

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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.