refactor: deduplicate tx request preparation

[alxdca]

Summary

• Add shared contract transaction request helpers in src/contractTransactionRequests.ts.
• Replace repeated encode/upgrade-executor/prepare-transaction request logic across owner, sequencer inbox, rollup admin, aggregator, and action builders.

Why / Context

• Several transaction request builders were manually repeating the same flow: encode contract call data, optionally wrap it through the upgrade executor, prepare the transaction request, and return the request with chainId.
• Centralizing that flow reduces duplicated implementation code while keeping call-specific ABI, target address, account, gas, and upgrade executor parameters explicit at each call site.