[Feat]Add link to show all Issues/PullRequests (#4125)

The Issue and PullRequest list has 3 states:
- open: This lists all open Issues/PullRequests
- closed: This lists all closed Issues/PullRequests
- all: This lists all open and closed Issues/PullRequests

If you want to get to the all state, you need to click Open while in open state or Closed while in closed state, which is very unintuitive. This PR adss a third button to get to this state.

![grafik](/attachments/4ff59e4c-e318-40f0-80ba-f921ce098919)

I'm not sure if the eye icon fits well, but I couldn't find a better one.

Tests will be added once #4124 is merged.

Reviewed-on: https://codeberg.org/forgejo/forgejo/pulls/4125
Reviewed-by: Earl Warren <earl-warren@noreply.codeberg.org>
Co-authored-by: JakobDev <jakobdev@gmx.de>
Co-committed-by: JakobDev <jakobdev@gmx.de>

models/issues/issue_stats.go

@@ -15,13 +15,13 @@ import (
 
 // IssueStats represents issue statistic information.
 type IssueStats struct {
-	OpenCount, ClosedCount int64
-	YourRepositoriesCount  int64
-	AssignCount            int64
-	CreateCount            int64
-	MentionCount           int64
-	ReviewRequestedCount   int64
-	ReviewedCount          int64
+	OpenCount, ClosedCount, AllCount int64
+	YourRepositoriesCount            int64
+	AssignCount                      int64
+	CreateCount                      int64
+	MentionCount                     int64
+	ReviewRequestedCount             int64
+	ReviewedCount                    int64
 }
 
 // Filter modes.
@@ -104,6 +104,7 @@ func GetIssueStats(ctx context.Context, opts *IssuesOptions) (*IssueStats, error
 		}
 		accum.OpenCount += stats.OpenCount
 		accum.ClosedCount += stats.ClosedCount
+		accum.AllCount += stats.AllCount
 		accum.YourRepositoriesCount += stats.YourRepositoriesCount
 		accum.AssignCount += stats.AssignCount
 		accum.CreateCount += stats.CreateCount
@@ -131,7 +132,13 @@ func getIssueStatsChunk(ctx context.Context, opts *IssuesOptions, issueIDs []int
 	stats.ClosedCount, err = applyIssuesOptions(sess, opts, issueIDs).
 		And("issue.is_closed = ?", true).
 		Count(new(Issue))
-	return stats, err
+	if err != nil {
+		return stats, err
+	}
+
+	stats.AllCount = stats.OpenCount + stats.ClosedCount
+
+	return stats, nil
 }
 
 func applyIssuesOptions(sess *xorm.Session, opts *IssuesOptions, issueIDs []int64) *xorm.Session {