Add issue events filter and make sure "All" really shows everything

Currently, the EventFilter whitelists event types for the "All" filter.
This has gotten outdated, which causes the confusing behaviour of the
"All" tab not really showing all events. To make matters worse, by
default no tab at all is selected, which does show all events, so
selecting the "All" tab actually hides some events.

Fix this by:
- Making sure All always includes all activity, by abolishing the
  whitelist and just returning all events instead.
- Make the All tab selected by default.
- Add Issue events tab to include the specific events around opening
  and closing issues, since there was no specific filter to see them
  yet.

Fixes #24826

lib/event_filter.rb

@@ -14,6 +14,10 @@ class EventFilter
       'merged'
     end
 
+    def issue
+      'issue'
+    end
+
     def comments
       'comments'
     end
@@ -32,32 +36,20 @@ class EventFilter
   end
 
   def apply_filter(events)
-    return events unless params.present?
+    return events if params.blank? || params == EventFilter.all
 
-    filter = params.dup
-    actions = []
-
-    case filter
+    case params
     when EventFilter.push
-      actions = [Event::PUSHED]
+      events.where(action: Event::PUSHED)
     when EventFilter.merged
-      actions = [Event::MERGED]
+      events.where(action: Event::MERGED)
     when EventFilter.comments
-      actions = [Event::COMMENTED]
+      events.where(action: Event::COMMENTED)
     when EventFilter.team
-      actions = [Event::JOINED, Event::LEFT, Event::EXPIRED]
-    when EventFilter.all
-      actions = [
-        Event::PUSHED,
-        Event::MERGED,
-        Event::COMMENTED,
-        Event::JOINED,
-        Event::LEFT,
-        Event::EXPIRED
-      ]
+      events.where(action: [Event::JOINED, Event::LEFT, Event::EXPIRED])
+    when EventFilter.issue
+      events.where(action: [Event::CREATED, Event::UPDATED, Event::CLOSED, Event::REOPENED])
     end
-
-    events.where(action: actions)
   end
 
   def options(key)
@@ -73,6 +65,10 @@ class EventFilter
   end
 
   def active?(key)
-    params.include? key
+    if params.present?
+      params.include? key
+    else
+      key == EventFilter.all
+    end
   end
 end