when explorer.baseUrl is empty or blank, which is a misconfigured app rather than a
missing link.
getExplorerLink({ explorer, value: partyId })
// 'https://scan.example/party/…', the party shape having matched on its own
getExplorerLink({ explorer, value: '1220df94a1', entity: 'update' })
// 'https://scan.example/update/1220df94a1', the entity overriding a shape that matched nothing
getExplorerLink({ explorer, value: 'nico' })
// undefined: no shape matched, and no entity said otherwise
Builds an explorer URL for a Canton identifier. Returns
undefinedwhenever no link can be made.