Add Joke Service and Tests

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Acceptance Criteria:

• [ ] There is JokeQueryService.java file in the src/main/java/edu/ucsb/cs156/spring/backend/services directory.
• [ ] JokeQueryService.java implements a class that make a call to the appropriate API and returns the results.
• [ ] There is JokeQueryServiceTests.java file in the src/test/java/edu/ucsb/cs156/spring/backend/services directory.
• [ ] The tests in JokeQueryServiceTests.java provide 100% coverage of JokeQueryService.java for both jacoco and pitest.

Details

See the assignment description at https://ucsb-cs156.github.io/w24/lab/team01 for details.