Introduce `Account` and `BucketMetadata`

[shichanglin5]

What problem are we solving?

Introduce Account to ensure that the account structure is consistent with Amazon S3, so as to ensure that multiple IAM-Users under one user account execute results in S3 ACL as expected

In Amazon S3, each user corresponds to an Account, and each Account can be configured with multiple IAM-Users. In S3 Access Control Policy(ACP), Account is used as the Owner of bucket and object, not IAM -User (using IAM-User as Owner will cause different IAM-Users of the same Account to have problems with ACL authentication)

How are we solving the problem?

Account is used as the owner of buckets and objects, not IAM-User, so that the ACL verify results of multiple IAM-Users under one account are consistent

How is the PR tested?

Checks

• [ ] I have added unit tests if possible.
• [ ] I will add related wiki document changes and link to this PR after merging.