Add contracts endpoint by address

[moisses89]

What is needed?

Implement the contracts endpoint by id following the same structure than https://safe-transaction-mainnet.safe.global/#/contracts/contracts_retrieve with multichain support.

Proposal multichain support

I would like to add the multichain support by default for this and other endpoints and filter by query param the chain that the client wants.
For example:
GET contracts/{address}/?chain_id=chain_id If chain_id is not used to filter the endpoint should return all the contract and abis for all the chains where the contract is supported.
If chain_id is used to filter just return the corresponding chain
Even we could think about add the chain_id as an array parameter to get a group of chains.

Tasks

• Add the necessary models (chains, Contracts, Abis... )
• Add the tests and factory for the added models
• Add the endpoint contract by address
• Add test for the implemented endpoint