Refactor `gnosis_safe_proxy_factory` -> `gnosis_safe_multisig`

[jmoreira-valory]

Refactor gnosis_safe_proxy_factory -> gnosis_safe_multisig

gnosis_safe_proxy_factory is a very bad name choice. Gnosis safe proxy factory is a native Safe contract, whereas ours is called GnosisSafeMultisig.

See also:

• Refactor gnosis_safe_proxy_factory -> gnosis_safe_multisig open-autonomy#2287
• https://github.com/valory-xyz/olas-operate-app/pull/258/files#r1702118215