Replace final_on_strong_qc_block_num in finality digest calculation and instead add other needed data

[arhag]

Depends on #377.

Remove final_on_strong_qc_block_num from finality_digest_data_v1.

Then add the following into level_3_commitments:

• latest_qc_claim_block_num
• latest_qc_claim_finality_digest
• latest_qc_claim_timestamp
• timestamp: This is the timestamp of the current block.

Also remove final_on_strong_qc_block_num from finality_data and instead add latest_qc_claim_block_num, latest_qc_claim_finality_digest, and latest_qc_claim_timestamp to finality_data.