Enhance GetStatsCmd to include additional options for backlog statistics

[freeznet]

fix https://github.com/streamnative/pulsarctl/issues/1800

• Added flags for precise backlog size, subscription backlog size, and earliest time in backlog.
• Updated doGetStats function to accept new parameters and utilize them in the stats retrieval process.
• Modified calls to GetPartitionedStats and GetStats to use the new options structure.

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[github-actions[bot]]

@freeznet:Thanks for your contribution. For this PR, do we need to update docs? (The PR template contains info about doc, which helps others know more about the changes. Can you provide doc-related info in this and future PR descriptions? Thanks)