BACK-6974: New schema for EIP712

[ClaireGuerreGiordano]

This PR aims to add additional schema for EIP712 as specified here
Diff with former schema are there additional properties:

                                                "assetPath": {
                                                    "type": "string"
                                                },
                                                "datetime": {
                                                    "format": "date-time",
                                                    "type": "string"
                                                },
                                                "format": {
                                                    "enum": [
                                                        "token",
                                                        "amount"
                                                    ]
                                                },
                                                "raw": {
                                                    "type": "string"
                                                }

[jnicoulaud-ledger]

Can you please add a description to your PR referencing specs for proper historization ? Thanks!

Adding diff of the schema for clarity:

❯ difft ethereum/eip712.schema.json ethereum/eip712-v2.schema.json                                            back6974
ethereum/eip712-v2.schema.json --- JSON
34 34                                                 "properties": {
.. 35                                                     "assetPath": {
.. 36                                                         "type": "string"
.. 37                                                     },
.. 38                                                     "format": {
.. 39                                                         "enum": [
.. 40                                                             "coin",
.. 41                                                             "amount",
.. 42                                                             "address"
.. 43                                                         ]
.. 44                                                     },
35 45                                                     "label": {