Added new constants, messages key and new styling to fit the new design for CSV / XLS UI

BMS-182

Reviewer: Daniel Villafuerte
Added new attributes for the label printing POJO to be used for the new UI changes

BMS-182

Reviewer: Daniel Villafuerte
Modified UI design to fit the changes for PDF label and XLS/CSV design changes

BMS-182 / BMS-183

Reviewer: Daniel Villafuerte
Modified label printing service to handle new logic for CSV and XLS label generation
Added new test cases to cover new functions introduced in the label printing service

BMS-182 / BMS-183

Reviewer: Daniel Villafuerte
Modified the test case to use mockito.never in checking if a function is called or not

BMS-182 / BMS-183

Reviewer: Daniel Villafuerte
Code cleanup and added semicolons

BMS-182 / BMS-183

Reviewer: Daniel Villafuerte