Meta for arrays

Meta for coze arrays would be useful.

Meta should only be populated with values common to all cozies. Any values that are not common must be omitted.

For example, the following should have a meta of `"alg": "ES256", "iat": 1670950149,"tmb": "cLj8vsYtMBwYkzoFVZHBZo6SNL8wSdCIjCKAwXNuhOk","typ": "cyphr.me/msg/create"`

```JSON
[{
"pay": {
"msg": "1",
"alg": "ES256",
"iat": 1670950149,
"tmb": "cLj8vsYtMBwYkzoFVZHBZo6SNL8wSdCIjCKAwXNuhOk",
"typ": "cyphr.me/msg/create"
},
"sig": "v61PwMA2o6w7jz1Oibinoj3YhP40VWnjCNPRyvZ5-G7dBtPLfXpNNRF3dR_Ph-UQ_yNQZzc5x7P_wZDvkoFkDg"
},
{
"pay": {
"msg": "2",
"alg": "ES256",
"iat": 1670950149,
"tmb": "cLj8vsYtMBwYkzoFVZHBZo6SNL8wSdCIjCKAwXNuhOk",
"typ": "cyphr.me/msg/create"
},
"sig": "-Jibadhev0yLDXg8zjp13_6w1TFCrQZaFcG5ap0XA0SE3vDXJuXp6rYWWvbWyq1cOJepJEibFwDZQZytEZwiYw"
},
{
"pay": {
"msg": "3",
"alg": "ES256",
"iat": 1670950149,
"tmb": "cLj8vsYtMBwYkzoFVZHBZo6SNL8wSdCIjCKAwXNuhOk",
"typ": "cyphr.me/msg/create"
},
"sig": "CYvvuDEDPtjJrtbCjl5eLaVgODAwNJj6KuHxqod3c4c8g5ijE3WyhsS9qBrPEtvkDD5qgltiDu_SQ7dqQesX0g"
}]
```