Worktime tracking for the organization level (#19808)

Dear Gitea team,

first of all, thanks for the great work you're doing with this project.

I'm planning to introduce Gitea at a client site, and noticed that while
there is time recording, there are no project-manager-friendly reports
to actually make use of that data, as were also mentioned by others in
#4870 #8684 and #13531.

Since I had a little time last weekend, I had put together something
that I hope to be a useful contribution to this great project (while of
course useful for me too).

This PR adds a new "Worktime" tab to the Organisation level. There is a
date range selector (by default set to the current month), and there are
three possible views:

- by repository,
- by milestone, and
- by team member.

Happy to receive any feedback!

There are several possible future improvements of course (predefined
date ranges, charts, a member time sheet, matrix of repos/members, etc)
but I hope that even in this relatively simple state this would be
useful to lots of people.

<img width="1161" alt="Screen Shot 2022-05-25 at 22 12 58"
src="https://user-images.githubusercontent.com/118010/170366976-af00c7af-c4f3-4117-86d7-00356d6797a5.png">

Keep up the good work!

Kristof

---------

Co-authored-by: user <user@kk-git1>
Co-authored-by: wxiaoguang <wxiaoguang@gmail.com>

templates/repo/issue/sidebar/stopwatch_timetracker.tmpl

@@ -72,7 +72,7 @@
 	{{end}}
 	{{if .WorkingUsers}}
 		<div class="ui comments tw-mt-2">
-			{{ctx.Locale.Tr "repo.issues.time_spent_from_all_authors" ($.Issue.TotalTrackedTime | Sec2Time)}}
+			{{ctx.Locale.Tr "repo.issues.time_spent_from_all_authors" ($.Issue.TotalTrackedTime | Sec2Hour)}}
 			<div>
 				{{range $user, $trackedtime := .WorkingUsers}}
 					<div class="comment tw-mt-2">
@@ -82,7 +82,7 @@
 						<div class="content">
 							{{template "shared/user/authorlink" $user}}
 							<div class="text">
-								{{$trackedtime|Sec2Time}}
+								{{$trackedtime|Sec2Hour}}
 							</div>
 						</div>
 					</div>