Bubblegum: Refactor MetadataArgs to be wrapper around Metadata

[ngundotra]

This refactor is meant to deduplicate code by using the validation methods in Metadata.

Roughly accomplished as follows:

• MetadataArgs + token ownership info ==> MetaplexMetadata
• MetaplexMetadata performs validation checks for collection information, etc
• MetaplexMetadata performs LeafSchema V0 validation checks on to_leaf_schema_v0

[github-actions]

Workflow Verify package library found differences when running yarn api:gen in the JS lib for bubblegum. Please see the job for more details: https://github.com/metaplex-foundation/metaplex-program-library/actions/runs/4266168783.

[ngundotra]

If this looks good, I'll refactor the process_collection_verification_mpl_only and process_creator_verification