Support transactional methods in EncryptionClient

### Problem:

- [transact_get_items()](https://boto3.amazonaws.com/v1/documentation/api/latest/reference/services/dynamodb.html#DynamoDB.Client.transact_get_items)
- [transact_write_items()](https://boto3.amazonaws.com/v1/documentation/api/latest/reference/services/dynamodb.html#DynamoDB.Client.transact_write_items)

Are not currently supported by the `EncryptionClient` and passed through to the underlying client.

### Solution:

Fully implement `transact_get_items()` and `transact_write_items()` in the `EncryptionClient`

### Out of scope:

Is there anything the solution will intentionally NOT address? No

### Workaround

I was able to implement the following workaround to encrypt one of the `Put` requests within my transaction:

```
aws_kms_cmp = AwsKmsCryptographicMaterialsProvider(key_id=KEY_ARN)
actions = AttributeActions(
default_action=CryptoAction.DO_NOTHING,
attribute_actions={"access_token": CryptoAction.ENCRYPT_AND_SIGN},
)
encrypted_client = EncryptedClient(
client=dynamodb.meta.client,
materials_provider=aws_kms_cmp,
attribute_actions=actions,
expect_standard_dictionaries=True,
auto_refresh_table_indexes=False
)

item = {
"pk": f"USER#{user_id}#ITEM#{item_id}",
"sk": "v0",
"access_token": access_token,
"institution_id": institution_id,
"institution_name": institution.get("name"),
"link_session_id": metadata.get("link_session_id"),
"created_at": now,
}

def mock_write_method(**kwargs):
return kwargs.get("Item")

encrypt_item = partial(
encrypt_put_item,
encrypted_client._encrypt_item,
encrypted_client._item_crypto_config,
mock_write_method,
)
encrypted_item = encrypt_item(TableName=TABLE_NAME, Item=item)

items = [
{
"Put": {
"TableName": TABLE_NAME,
"Item": encrypted_item
}
}
]
dynamodb_client.transact_write_items(TransactItems=items)
```

Start at the EncryptionClient entry point and inspect how its existing DynamoDB operations interact with the underlying client. Compare the transact_get_items() and transact_write_items() AWS APIs with the workaround shown; done means both methods are fully supported instead of being passed through.

索引モデルが issue の本文から書いたものです。