Localize time units on activity heatmap (#21570)

Previously, the months and days were hardcoded into English

* Closes #15541

## Screenshots
### English

![image](https://user-images.githubusercontent.com/20454870/197410352-1b28a637-ce19-41ae-b4e5-27955555b082.png)

### German

![image](https://user-images.githubusercontent.com/20454870/197410455-f243ca84-807f-476e-b8ed-c24e827bfc2d.png)

### Spanish

![image](https://user-images.githubusercontent.com/20454870/197410366-55202ca5-08f9-4152-8f9d-d5eeebd532ef.png)

### Italian

![image](https://user-images.githubusercontent.com/20454870/197410385-75f754dd-e845-4444-8a04-472a8f45b617.png)

### Portuguese
This one has a bit of overflow

![image](https://user-images.githubusercontent.com/20454870/197410414-b91f962e-77e9-4cc7-990b-01c0fc0cbd0b.png)

Signed-off-by: Yarden Shoham <hrsi88@gmail.com>
Co-authored-by: Gusted <williamzijl7@hotmail.com>
Co-authored-by: silverwind <me@silverwind.io>
Co-authored-by: Lunny Xiao <xiaolunwen@gmail.com>
Co-authored-by: techknowlogick <techknowlogick@gitea.io>

web_src/js/features/heatmap.js

@@ -1,6 +1,6 @@
 import {createApp} from 'vue';
 import ActivityHeatmap from '../components/ActivityHeatmap.vue';
-
+import {translateMonth, translateDay} from '../utils.js';
 export default function initHeatmap() {
   const el = document.getElementById('user-heatmap');
   if (!el) return;
@@ -17,7 +17,14 @@ export default function initHeatmap() {
       return {date: new Date(v), count: heatmap[v]};
     });
 
-    const View = createApp(ActivityHeatmap, {values});
+    const locale = {
+      months: new Array(12).fill().map((_, idx) => translateMonth(idx)),
+      days: new Array(7).fill().map((_, idx) => translateDay(idx)),
+      contributions: 'contributions',
+      no_contributions: 'No contributions',
+    };
+
+    const View = createApp(ActivityHeatmap, {values, locale});
 
     View.mount(el);
   } catch (err) {