Correct identifiers in metadata

[jonrkarr]

This pertains to

https://github.com/biosimulations/biosimulations-physiome/blob/dev/biosimulations_physiome/process_projects.py#L139

• The identifiers need to account for the namespace of each project (e or exposure)
• Only the exposure namespace is current registered with identifiers.org. Until this is changed, lets use the direct URLs such as
  • https://models.physiomeproject.org/e/123
  • https://models.physiomeproject.org/exposure/xxxxxxxxxxxxxx