Resolve mismatch between FeedbackSession and FeedbackSessionAttributes isClosed, isOpened, isInGracePeriod

[FergusMok]

Currently, there's a mismatch in behavior of the methods during the migration.
FeedbackSession only takes into account endTime, but the original method takes into account graceTime, deadlineExtensions and endTime.

teammates/src/main/java/teammates/storage/sqlentity/FeedbackSession.java

Lines 454 to 477 in d6c67fc

	/**
	* Checks if the feedback session is closed.
	* This occurs only when the current time is after both the deadline and the grace period.
	*/
	public boolean isClosed() {
	return !isOpened() && Instant.now().isAfter(endTime);
	}
	/**
	* Checks if the feedback session is open.
	* This occurs when the current time is either the start time or later but before the deadline.
	*/
	public boolean isOpened() {
	Instant now = Instant.now();
	return (now.isAfter(startTime) || now.equals(startTime)) && now.isBefore(endTime);
	}
	/**
	* Checks if the feedback session is during the grace period.
	* This occurs when the current time is after end time, but before the end of the grace period.
	*/
	public boolean isInGracePeriod() {
	return Instant.now().isAfter(endTime) && !isClosed();
	}

teammates/src/main/java/teammates/common/datatransfer/attributes/FeedbackSessionAttributes.java

Lines 318 to 344 in d6c67fc

	/**
	* Checks if the feedback session is closed.
	* This occurs when the current time is after both the deadline and the grace period.
	*/
	public boolean isClosed() {
	return Instant.now().isAfter(getDeadline().plus(gracePeriod));
	}
	/**
	* Checks if the feedback session is open.
	* This occurs when the current time is either the start time or later but before the deadline.
	*/
	public boolean isOpened() {
	Instant now = Instant.now();
	return (now.isAfter(startTime) || now.equals(startTime)) && now.isBefore(getDeadline());
	}
	/**
	* Checks if the feedback session is closed but still accepts responses.
	* This occurs when the current time is either the deadline or later but still within the grace period.
	*/
	public boolean isInGracePeriod() {
	Instant now = Instant.now();
	Instant deadline = getDeadline();
	Instant gracedEnd = deadline.plus(gracePeriod);
	return (now.isAfter(deadline) || now.equals(deadline)) && (now.isBefore(gracedEnd) || now.equals(gracedEnd));
	}

The actual behavior should instead use these methods:

teammates/src/main/java/teammates/storage/sqlentity/FeedbackSession.java

Lines 486 to 511 in d6c67fc

	/**
	* Checks if the feedback session is opened given the extendedDeadline and grace period.
	*/
	public boolean isOpenedGivenExtendedDeadline(Instant extendedDeadline) {
	Instant now = Instant.now();
	return (now.isAfter(startTime) || now.equals(startTime))
	&& now.isBefore(extendedDeadline.plus(gracePeriod)) || now.isBefore(endTime.plus(gracePeriod));
	}
	/**
	* Checks if the feedback session is closed given the extendedDeadline and grace period.
	* This occurs only when it is after the extended deadline or end time plus grace period.
	*/
	public boolean isClosedGivenExtendedDeadline(Instant extendedDeadline) {
	Instant now = Instant.now();
	return !isOpenedGivenExtendedDeadline(extendedDeadline)
	&& now.isAfter(endTime.plus(gracePeriod)) && now.isAfter(extendedDeadline.plus(gracePeriod));
	}
	/**
	* Checks if the feedback session is during the grace period given the extendedDeadline.
	*/
	public boolean isInGracePeriodGivenExtendedDeadline(Instant extendedDeadline) {
	Instant now = Instant.now();
	return now.isAfter(endTime) && now.isAfter(extendedDeadline) && !isClosedGivenExtendedDeadline(extendedDeadline);
	}

Impact of bug
During the migration, due to similarity in names, some migrated actions are utilizing the wrong method.

Suggested change

1. As the FeedbackSessionAttributes did not need a separate isXXXGivenExtendedDeadline set of methods, a suggestion is to rename them inFeedbackSession and make the method signatures match the set of methods in FeedbackSessionAttributes.
2. Implement additional unit tests if need be.