Improve the explanation of proof verification

[ernestognw]

Description

Right now, the verifier is still an MVP, although it's enough to show why a signature or a document is proven, we need to add more interactive elements and checks for each of the elements.

Some ideas:

• Verify the OCSP response using a ocsp library on the frontend
• Run the signature verification in the browser
• Verify the signer certificate against the certification service provider certificates from IES
• Add explanations of how components are related (e.g. how the hash is related to the signature, or how the PKI depends on signatures from certified providers and the central bank)