test: migrate ProcessingTest to JUnit 5

[MartinWitt]

#3919

The following has changed in the code:

Junit4 @test Annotation

• Replaced junit 4 test annotation with junit 5 test annotation in testInsertBegin
• Replaced junit 4 test annotation with junit 5 test annotation in testInsertEnd
• Replaced junit 4 test annotation with junit 5 test annotation in testProcessorNotFoundThrowAnException
• Replaced junit 4 test annotation with junit 5 test annotation in testProcessorWithNoArgumentsInConstructor
• Replaced junit 4 test annotation with junit 5 test annotation in testInitProperties
• Replaced junit 4 test annotation with junit 5 test annotation in testInitPropertiesWithWrongType
• Replaced junit 4 test annotation with junit 5 test annotation in testInitPropertiesWithStringType
• Replaced junit 4 test annotation with junit 5 test annotation in testProcessorWithGenericType
• Replaced junit 4 test annotation with junit 5 test annotation in testCallProcessorWithMultipleTypes
• Replaced junit 4 test annotation with junit 5 test annotation in testProcessDontMessWithImports
• Replaced junit 4 test annotation with junit 5 test annotation in testNullableSettingForProcessor
• Replaced junit 4 test annotation with junit 5 test annotation in testNullableSettingForProcessor2

AssertionsTransformation

• Transformed junit4 assert to junit 5 assertion in testInsertBegin
• Transformed junit4 assert to junit 5 assertion in testInsertEnd
• Transformed junit4 assert to junit 5 assertion in testProcessorNotFoundThrowAnException
• Transformed junit4 assert to junit 5 assertion in testProcessorWithNoArgumentsInConstructor
• Transformed junit4 assert to junit 5 assertion in testInitProperties
• Transformed junit4 assert to junit 5 assertion in testInitPropertiesWithWrongType
• Transformed junit4 assert to junit 5 assertion in testInitPropertiesWithStringType
• Transformed junit4 assert to junit 5 assertion in testProcessorWithGenericType
• Transformed junit4 assert to junit 5 assertion in testCallProcessorWithMultipleTypes
• Transformed junit4 assert to junit 5 assertion in testProcessDontMessWithImports
• Transformed junit4 assert to junit 5 assertion in testNullableSettingForProcessor