Add V2 for multisigtransaction and all-transactions endpoints

[moisses89]

Description

Add V2 endpoint for the new return types on multisigtransaction.

Marking as deprecated the following endpoints

• GET /api/v1/multisig-transactions/{safe_tx_hash}/
• DELETE /api/v1/multisig-transactions/{safe_tx_hash}/
• GET /api/v1/safes/{address}/multisig-transactions/
• POST /api/v1/safes/{address}/multisig-transactions/
• GET /api/v1/safes/{address}/all-transactions/

V2 of new endpoints

• GET /api/v2/multisig-transactions/{safe_tx_hash}/
• DELETE /api/v2/multisig-transactions/{safe_tx_hash}/
• GET /api/v2/safes/{address}/multisig-transactions/
• POST /api/v2/safes/{address}/multisig-transactions/
• GET /api/v2/safes/{address}/all-transactions/

Version2 types

The endpoints behind version two modify the types int for string for the following properties.

 nonce : <String>
 base_gas : <String>
 safe_tx_gas : <String>

[JagoFigueroa]

Looking good to me, will be sure to test them on UI too once the v2 are enabled there too