Get object size metadata type differs between storage providers

For example: when using Openstack Swift, object size is returned as an integer but when using Amazon S3 its returned as a string.

This seems to be the case for other storage providers as well. In the implementation for Atmos and Aliyun OSS, the object size metadata is explicitly converted to an integer. This is not the case for other storage providers like BackblazeB2 or Amazon S3.