Localize activity heatmap (except tooltip) (#24131)

The calculation of the total sum is moved to the backend so a full HTML
string could be sent.


![image](https://user-images.githubusercontent.com/20454870/232112381-c11d896b-ba47-40f8-b2a3-71cf4b3208de.png)

- Closes #10669
- 2nd attempt (the first was in #21570)

---------

Signed-off-by: Yarden Shoham <git@yardenshoham.com>
Co-authored-by: Giteabot <teabot@gitea.io>

models/activities/user_heatmap.go

@@ -69,3 +69,12 @@ func getUserHeatmapData(user *user_model.User, team *organization.Team, doer *us
 		OrderBy("timestamp").
 		Find(&hdata)
 }
+
+// GetTotalContributionsInHeatmap returns the total number of contributions in a heatmap
+func GetTotalContributionsInHeatmap(hdata []*UserHeatmapData) int64 {
+	var total int64
+	for _, v := range hdata {
+		total += v.Contributions
+	}
+	return total
+}