fix(transaction): implement EIP-1559 compliant fee calculation

[gacevicljubisa]

Checklist

• [x] I have read the coding guide.
• [ ] My change requires a documentation update, and I have done it.
• [ ] I have added tests to cover my changes.
• [x] I have filled out the description and linked the related issues.

Description

This PR refactors the gas cost estimation to be fully EIP-1559 compliant. The previous implementation relied on the outdated legacy SuggestGasPrice method, which provided inaccurate estimates for the required gas funds.

• suggestedFeeAndTip is modified
• This function calculates an estimated transaction cost by using the latest block's baseFee and a suggested tip (SuggestGasTipCap).
• the estimation uses a buffered baseFee plus the tip (gasFeeCap = (2 * baseFee) + gasTipCap)
• SuggestGasPrice is removed from suggestedFeeAndTip

Open API Spec Version Changes (if applicable)

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