[Feature] Impl GasEstimatorLayer

[yash-atreya]

Component

provider, pubsub

Describe the feature you would like

Just like how ManagedNonceLayer automatically manages the nonce field in TransactionRequest if unset by the user. GasEstimatorLayer would populate the gas_price, gas, max_fee_per_gas and max_priority_fee_per_gas.

Using this layer would remove the need for users to set these critical fields themselves.

Additional context

No response