Perform clean up - integrate with storage interface, remove custom I/O classes

[mcember]

The goal of this ticket is to remove classes which are irrelevant/obsolete after the deltacat/rivulet metastore unification. Also - we should fully reconcile the code within rivulet which produces metafiles with storage/interface.py (and storage/main/impl.py implementation)

Acceptance Criteria:

• All access of metastore files replaced with storage interface calls
• Remove unecessary wrappers around metastore, like the DatasetMetastore class
• Remove unecessary file IO classes/utilities like InputFile, OutputFile, FileStore, FileProvider