Encryption headers only partially stored and returned

[afranken]

APIs like PutObject let customers send headers starting with x-amz-server-side-encryption, APIs like GetObject and HeadObject should return them
From PutObject

x-amz-server-side-encryption: ServerSideEncryption
x-amz-server-side-encryption-customer-algorithm: SSECustomerAlgorithm
x-amz-server-side-encryption-customer-key-MD5: SSECustomerKeyMD5
x-amz-server-side-encryption-aws-kms-key-id: SSEKMSKeyId
x-amz-server-side-encryption-context: SSEKMSEncryptionContext
x-amz-server-side-encryption-bucket-key-enabled: BucketKeyEnabled

Currently, S3Mock only accepts the x-amz-server-side-encryption and x-amz-server-side-encryption-aws-kms-key-id, values are stored and returned.

S3Mock should accept all encryption headers and return them.