Issue time estimate, meaningful time tracking (#23113)

Redesign the time tracker side bar, and add "time estimate" support (in "1d 2m" format)

Closes #23112

---------

Co-authored-by: stuzer05 <stuzer05@gmail.com>
Co-authored-by: Yarden Shoham <hrsi88@gmail.com>
Co-authored-by: silverwind <me@silverwind.io>
Co-authored-by: 6543 <6543@obermui.de>
Co-authored-by: wxiaoguang <wxiaoguang@gmail.com>

models/issues/issue.go

@@ -147,6 +147,9 @@ type Issue struct {
 
 	// For view issue page.
 	ShowRole RoleDescriptor `xorm:"-"`
+
+	// Time estimate
+	TimeEstimate int64 `xorm:"NOT NULL DEFAULT 0"`
 }
 
 var (
@@ -934,3 +937,28 @@ func insertIssue(ctx context.Context, issue *Issue) error {
 
 	return nil
 }
+
+// ChangeIssueTimeEstimate changes the plan time of this issue, as the given user.
+func ChangeIssueTimeEstimate(ctx context.Context, issue *Issue, doer *user_model.User, timeEstimate int64) error {
+	return db.WithTx(ctx, func(ctx context.Context) error {
+		if err := UpdateIssueCols(ctx, &Issue{ID: issue.ID, TimeEstimate: timeEstimate}, "time_estimate"); err != nil {
+			return fmt.Errorf("updateIssueCols: %w", err)
+		}
+
+		if err := issue.LoadRepo(ctx); err != nil {
+			return fmt.Errorf("loadRepo: %w", err)
+		}
+
+		opts := &CreateCommentOptions{
+			Type:    CommentTypeChangeTimeEstimate,
+			Doer:    doer,
+			Repo:    issue.Repo,
+			Issue:   issue,
+			Content: fmt.Sprintf("%d", timeEstimate),
+		}
+		if _, err := CreateComment(ctx, opts); err != nil {
+			return fmt.Errorf("createComment: %w", err)
+		}
+		return nil
+	})
+}