Add CLI commands to list and get memory events/records

## Description

There are no CLI commands to list or retrieve memory events and records. Having these commands would greatly help with debugging and troubleshooting memory-related issues.

## Steps to Reproduce

1. Add memory to an agent and run a session
2. Try to inspect the memory events or records via the CLI
3. Observe that no such commands exist

## Expected Behavior

CLI commands should be available to list and get memory events/records, e.g.:
- `agentcore memory list-events`
- `agentcore memory get-record `

## Actual Behavior

No CLI commands exist for inspecting memory events or records. Users have no easy way to debug memory behavior.

## CLI Version

_N/A_

## Operating System

macOS