Display pending verifiable credentials

[shjortConcordium]

Purpose

Display pending verifiable credentials.

Changes

• Add session storage for verifiable credential metadata.
• Use session stored metadata if credentialEntry is missing.
• Catch some errors in VC hooks.

Checklist

• My code follows the style of this project.
• The code compiles without warnings.
• I have performed a self-review of the changes.
• I have documented my code, in particular the intent of the
  hard-to-understand areas.
• (If necessary) I have updated the CHANGELOG.

[orhoj]

If I press the pending credential to see its details, then I get shown blank content. Probably because it expects something to load that won't load until it is on-chain.