rabbit_feature_flags: Expose more feature flag properties to the management API

[Why]
It allows to better communicate each feature flag specificities and make
a better more user-friendly management UI.

Author: dumbbell

deps/rabbit/src/rabbit_feature_flags.erl

@@ -348,6 +348,8 @@
               feature_state/0,
               feature_states/0,
               stability/0,
+              require_level/0,
+              experiment_level/0,
               callback_fun_name/0,
               callbacks/0,
               callback_name/0,

deps/rabbit/src/rabbit_ff_extra.erl

@@ -24,6 +24,12 @@
 -type cli_info_entry() :: [{name, rabbit_feature_flags:feature_name()} |
                            {state, enabled | disabled | unavailable} |
                            {stability, rabbit_feature_flags:stability()} |
+                           {require_level,
+                            rabbit_feature_flags:require_level()} |
+                           {experiment_level,
+                            rabbit_feature_flags:experiment_level()} |
+                           {callbacks,
+                            [rabbit_feature_flags:callback_name()]} |
                            {provided_by, atom()} |
                            {desc, string()} |
                            {doc_url, string()}].
@@ -61,6 +67,11 @@ cli_info(FeatureFlags) ->
               FeatureProps = maps:get(FeatureName, FeatureFlags),
               State = rabbit_feature_flags:get_state(FeatureName),
               Stability = rabbit_feature_flags:get_stability(FeatureProps),
+              RequireLevel = rabbit_feature_flags:get_require_level(
+                               FeatureProps),
+              ExperimentLevel = rabbit_feature_flags:get_experiment_level(
+                                  FeatureProps),
+              Callbacks = maps:keys(maps:get(callbacks, FeatureProps, #{})),
               App = maps:get(provided_by, FeatureProps),
               Desc = maps:get(desc, FeatureProps, ""),
               DocUrl = maps:get(doc_url, FeatureProps, ""),
@@ -69,6 +80,9 @@ cli_info(FeatureFlags) ->
                         {doc_url, unicode:characters_to_binary(DocUrl)},
                         {state, State},
                         {stability, Stability},
+                        {require_level, RequireLevel},
+                        {experiment_level, ExperimentLevel},
+                        {callbacks, Callbacks},
                         {provided_by, App}],
               [FFInfo | Acc]
       end, [], lists:sort(maps:keys(FeatureFlags))).