QuantConnect Lean Fixes GetMarketHours Early Close and Late Open Edge Cases

QuantConnect Lean has fixed edge cases in the GetMarketHours function involving early closes and delayed opens, resolving the issue where a delayed open later than all sessions on a given day would return incorrect trading hours, while also eliminating anomalies with zero-length sessions at boundaries. This update adds corresponding regression tests covering scenarios such as delayed opens across multiple sessions and early closes followed by subsequent delayed opens.