[MM-41998] Channel Info RHS: display number of files for a channel (#19822)

Co-authored-by: Mattermod <mattermod@users.noreply.github.com>

store/storetest/mocks/ChannelStore.go

@@ -881,6 +881,27 @@ func (_m *ChannelStore) GetDeletedByName(team_id string, name string) (*model.Ch
 	return r0, r1
 }
 
+// GetFileCount provides a mock function with given fields: channelID
+func (_m *ChannelStore) GetFileCount(channelID string) (int64, error) {
+	ret := _m.Called(channelID)
+
+	var r0 int64
+	if rf, ok := ret.Get(0).(func(string) int64); ok {
+		r0 = rf(channelID)
+	} else {
+		r0 = ret.Get(0).(int64)
+	}
+
+	var r1 error
+	if rf, ok := ret.Get(1).(func(string) error); ok {
+		r1 = rf(channelID)
+	} else {
+		r1 = ret.Error(1)
+	}
+
+	return r0, r1
+}
+
 // GetForPost provides a mock function with given fields: postID
 func (_m *ChannelStore) GetForPost(postID string) (*model.Channel, error) {
 	ret := _m.Called(postID)