Use a behavior-driven naming convention for unit tests.
Functions are now named using the pattern: [unit]__[verb]__[scenario]
The __ works as a semantic separator.
Examples:
* jid_create__returns__null_from_null()
* cmd_connect__shows__usage_when_no_server_value
Benefits:
* Easy to find all tests associated with a specific function using the
mandatory prefix.
* Test output in CI now explicitly describes the unit, the expected
outcome, and the scenario being tested.
Also disabled keyhandlers tests due to missing code in src/ui.
e81435be06