Refactored Location and all associated classes.

[tsanevp]

Added javadoc and test cases as well. Added license to our States.java enums class.

Edits made to specific .java files & their purpose: Bot.java:

• Removed commented-out code that will never be used.

CreateListingCommand.java:

• Making the method buildListingEmbed @NonNull removed the need to check if the return value from the method is null.

Location.java:

• Added javadoc to each method to make code easier to follow
• Defined local variables as 'var' per lombok
• Defined variables used more than once to make code more readable in lines 66-70
• Removed try-catch since that was abstracted out into CensusService.java (lines 66-70)
• createCityMessageBuilder now is passed a stateAbbr instead of a Discord event. This makes it testable and also more readable

CityController.java:

• Added javadoc for readability & understanding

States.java:

• Added licenses to our code. Edits and changes have been made to the original to fulfill our needs
• Added javadoc

CityResponse.java:

• Renamed name to cityName to make code clearer and easier to differentiate between variables

LocationTest.java:

• Tested createStatesMessageBuilder() method in Location since it does not rely on discord. Can test to ensure the correct drop-down menus are created

Removed two old .java files that were fully commented out. Not needed.