Explorer improvements Cardano transactions

[jpraynaud]

Why

Following the completion of issue #1497, we want to make some improvements on the explorer.

What

Implement improvement in the Cardano transaction modal of the explorer.

How

• Add links to cexplorer for transactions
• Verify transaction proof before validating the certificate chain
• Display the beacon on which the verification takes place (latest at least of signed beacon in the artifact)
• Use the Mithril icon for validated transactions?
• Display more information about the certificates (epoch number, date of creation) in the verification modal
• Add a link to the certificate modal in the verification modal?
• Fix a display issue: when switching from an aggregator that have cardano transactions capabilities the tab container is empty.