Collection of small API changing improvements

[DOBEN]

Task description

Collection of API breaking improvements:

Sub-tasks

• Use rewardPeriodLength directly in latestChainParameters (remove ChainParametersV1) in https://github.com/Concordium/concordium-scan/blob/main/frontend/src/queries/useBakerQuery.ts
• Fix typos Cis2 instead of Cis in https://github.com/Concordium/concordium-scan/blob/main/frontend/src/queries/useTokenQuery.ts
• Rename CisEvent to Cis2TokenEvents (updateOperator events are not included).
• The front end only uses the lastPaydayBlock in PaydayStatus. Return the PaydaySummary of the lastPaydayBlock directly without the payday_summaries list.
• The function Baker::transactions can directly return a Transaction instead of the IterimTransaction type here.
• Rename Versions::backend_versions to Versions::backend_version.