[UI] Replace vue-bar-graph with chart.js

- Backport of #4571
- The usage of the `vue-bar-graph` is complicated, because of the `GSAP`
dependency they pull in, the dependency uses a non-free license.
- The code is rewritten to use the `chart.js` library, which is already
used to draw other charts in the activity tab. Due to the limitation of
`chart.js`, we have to create a plugin in order to have images as labels
and do click handling for those images.
- The chart isn't the same as the previous one, once again simply due to
how `chart.js` works, the amount of commits isn't drawn anymore in the
bar, you instead have to hover over it or look at the y-axis.
- Resolves #4569

(cherry picked from commit a83002679d)

options/locale/locale_en-US.ini

@@ -2116,6 +2116,7 @@ activity.git_stats_addition_n = %d additions
 activity.git_stats_and_deletions = and
 activity.git_stats_deletion_1 = %d deletion
 activity.git_stats_deletion_n = %d deletions
+activity.commit = Commit activity
 
 contributors.contribution_type.filter_label = Contribution type:
 contributors.contribution_type.commits = Commits