Add MultiCluster API changes support for key and bucket structs

[zliang-akamai]

📝 Description

What does this PR do and why is this change necessary?

✔️ How to Test

make ARGS="-run TestObjectStorageKeys_Regional" fixtures

make ARGS="-run TestObjectStorageBucket_Regional" fixtures

package main

import (
    "context"
    "fmt"
    "log"
    "net/http"
    "os"

    "github.com/linode/linodego"
    "golang.org/x/oauth2"
)

func main() {
    apiKey, ok := os.LookupEnv("LINODE_TOKEN")
    if !ok {
        log.Fatal("Could not find LINODE_TOKEN, please assert it is set.")
    }
    tokenSource := oauth2.StaticTokenSource(&oauth2.Token{AccessToken: apiKey})

    oauth2Client := &http.Client{
        Transport: &oauth2.Transport{
            Source: tokenSource,
        },
    }

    linodeClient := linodego.NewClient(oauth2Client)
    linodeClient.SetDebug(true)

    bucket, err := linodeClient.CreateObjectStorageBucket(
        context.Background(),
        linodego.ObjectStorageBucketCreateOptions{
            Label:  "test-mc-bucket",
            Region: "us-east",
        },
    )

    fmt.Printf("%v", bucket)
    fmt.Printf("%v", err)

    key, err := linodeClient.CreateObjectStorageKey(
        context.Background(),
        linodego.ObjectStorageKeyCreateOptions{
            Label: "test-key",
            BucketAccess: &[]linodego.ObjectStorageKeyBucketAccess{
                {
                    BucketName:  bucket.Label,
                    Permissions: "read_only",
                    Region:      "us-east",
                },
            },
            Regions: nil,
        },
    )

    fmt.Printf("%v", key)
    fmt.Printf("%v", err)

    linodeClient.DeleteObjectStorageBucket(context.Background(), "us-east", bucket.Label)
    linodeClient.DeleteObjectStorageKey(context.Background(), key.ID)
}