Improve backend test names to be more readable

[Velocities]

Many of our current existing tests for the Laravel API Controllers are poorly named, like testShowGroceryItem or testShowGroceryItemUnauthorized; to make debugging failed tests easier, backend tests should follow this naming convention: methodUnderTest_ScenarioName_ExpectedOutcome.

For example, the following test would be a good name for an alternative to testShowGroceryItemUnauthorized: show_unauthorizedUser_returns403Error.

By adopting this naming convention, we can ensure our test suite is easier to understand and maintain.

[Velocities]

Upon research throughout this process on testing units like Policies, another separate issue will be created for moving some of these tests to separate Feature test files and organizing them into folders for individual controller tests vs multiple controllers being tested in tandem/integrated. For this issue, the work has been complete and can be marked as such.