Health checks results report.
t() :: %Report{ checks: [atom()], failing: [atom()], http_code: 200 | 503, passing: [atom()], timeout: [atom()], warning: [atom()] }
build(checks :: [atom()]) :: t()
generate(report :: t()) :: {200, map()} | {503, map()}
report_failing(report :: t(), check :: atom(), result :: String.t()) :: t()
report_passing(report :: t(), check :: atom(), result :: String.t()) :: t()
report_timeout(report :: t()) :: t()
report_warning(report :: t(), check :: atom(), result :: String.t()) :: t()