feat: clean up meta for ERC-20 transfers

[paolodamico]

Changes

• Remove TransferSource from ERC-20 transfer meta. Following discussions, analytics (particularly optional ones) data should not go here.
• Remove Network parameter from transaction_transfer. World App only supports transfers on World Chain.
• Expose transfer_association in transaction_transfer such that World App can specify this metadata value.
• Removes rpc parameter from transaction_transfer. For the time being the selection of the RPC should be delegated to Bedrock, and Bedrock will have relevant logic for this. Right now, taking a default.

Note: while technically breaking API changes are being introduced, this API is not yet in use.

[Copilot]

Pull Request Overview

This PR cleans up the ERC-20 transfer metadata by removing analytics-focused fields and simplifying the API parameters. The changes focus on removing optional analytics data from the transfer metadata while exposing transfer association as a parameter for World App to specify.

• Removes TransferSource enum from ERC-20 transfer metadata as analytics data should not be stored here
• Simplifies transaction_transfer API by removing Network and rpc parameters since World App only supports World Chain
• Exposes transfer_association parameter to allow World App to specify metadata values

Reviewed Changes

Copilot reviewed 4 out of 4 changed files in this pull request and generated 2 comments.

File	Description
test_smart_account_transfer.rs	Updates test to use simplified API without Network and RPC parameters
transaction/mod.rs	Removes Network and RPC parameters, adds transfer_association parameter to transaction_transfer
transaction/contracts/erc20.rs	Removes TransferSource enum, shifts TransferAssociation to first metadata byte
smart_account/transaction_4337.rs	Reorders parameters in sign_and_execute method signature