QuantConnect Lean Fixes Edge Cases for Early Close and Delayed Open in GetMarketHours

QuantConnect Lean has resolved boundary anomalies in the GetMarketHours function related to early closes and delayed opens, fixing the error where a delayed open time later than all trading sessions on a given day would return the full regular trading session, while also eliminating the issue of zero-length trading sessions appearing at boundary time points. This fix adds corresponding regression tests, and the related changes have been merged into the codebase.