[Remote Store] Create abstraction for RemoteSegmentStoreDirectory.init() method

[sachinpkale]

Is your feature request related to a problem? Please describe.
As per the comment: #4253 (comment), this issue will create an abstraction for RemoteSegmentStoreDirectory.init() method. Having init() method open can create issues if caller does not handle it well. RemoteDirectory (or the Store enclosing it) should be in control of calling init() internally.