Update batching view methods for StakingRouter

[Psirex]

The main changes in the PR:

• add method getStakingModuleSummary(uint256 _stakingModuleId) into the StakingRouter to retrieve the validator's summary about the staking module in the form of struct StakingModuleSummary.

• add method getNodeOperatorSummary(uint256 _stakingModuleId, uint256 _nodeOperatorId) into the StakingRouter to retrieve the node operator's summary in the form of struct NodeOperatorSummary

• replace StakingModuleReport and NodeOperatorReport with StakingModuleDigest and NodeOperatorDigest accordingly. Here and below, the "digest" used in the meaning of "the compilation of main data"

• rename getAllStakingModuleReports(), getStakingModuleReports(), getAllNodeOperatorReports(), and getNodeOperatorReports() into getAllStakingModuleDigests(), getStakingModuleDigests(), getAllNodeOperatorDigests(), and getNodeOperatorDigests() accordingly.

[TheDZhon]

Let's get it merged 👍