Resolve "Generate Jitsi links for hybrid labs"

What does this mr do?

Makes sure that hybrid labs can be created. This means that a jitsi link can be generated if the location selected is "Online @ Jitsi". In other cases, no jitsi link will be created. This feature will eliminate the need to create 2 lab sessions (1 for online and 1 for physical) when a lab is hybrid.

Screenshots

before

after

Does this MR meet the acceptance criteria?

• I have added a changelog entry to reflect the significant changes I made.
• Tests were created to test the feature.
• I have updated the documentation accordingly.
• I adhere to the style guide.

src/main/java/nl/tudelft/queue/dto/create/labs/CapacitySessionCreateDTO.java

@@ -55,6 +55,8 @@ public class CapacitySessionCreateDTO extends QueueSessionCreateDTO<CapacitySess
 	public void validate() {
 		super.validate();
 
+		nonEmpty("rooms", rooms);
+
 		if (capacitySessionConfig.getEnrolmentClosesAt()
 				.isBefore(capacitySessionConfig.getEnrolmentOpensAt())) {
 			errors.rejectValue("capacitySessionConfig.enrolmentClosesAt",