feat (help): allow cli option to list tasks with no desc

added an add'l cli option that lists all tasks, with or without description.
orig. behavior: task -l lists tasks with desc field
new behaviour: task -la or task -a will list all tasks. if task has desc, it will be included.

BREAKING CHANGES: none, that I know of.
NOTES/Concerns:
- This is wip.
- Haven't checked how it interacts with bash completion.
- The new Executor.TaskNames func does not use e.CompiledTask(taskfile.Call{Task: task.Task})

help.go

@@ -9,10 +9,19 @@ import (
 	"github.com/go-task/task/v3/taskfile"
 )
 
-// PrintTasksHelp prints help os tasks that have a description
-func (e *Executor) PrintTasksHelp() {
-	tasks := e.tasksWithDesc()
+// PrintTasksHelp prints tasks' help.
+// Behavior is governed by listAll. When false, only tasks with descriptions are reported.
+// When true, all tasks are reported with descriptions shown where available.
+func (e *Executor) PrintTasksHelp(listAll bool) {
+	var tasks []*taskfile.Task
+	if listAll == true {
+		tasks = e.taskNames()
+	} else {
+		tasks = e.tasksWithDesc()
+	}
+
 	if len(tasks) == 0 {
+		// TODO: This message should be more informative. Maybe a hint to try -la for showing all?
 		e.Logger.Outf(logger.Yellow, "task: No tasks with description available")
 		return
 	}
@@ -26,6 +35,15 @@ func (e *Executor) PrintTasksHelp() {
 	w.Flush()
 }
 
+func (e *Executor) taskNames() (tasks []*taskfile.Task) {
+	tasks = make([]*taskfile.Task, 0, len(e.Taskfile.Tasks))
+	for _, task := range e.Taskfile.Tasks {
+		tasks = append(tasks, task)
+	}
+	sort.Slice(tasks, func(i, j int) bool { return tasks[i].Task < tasks[j].Task })
+	return
+}
+
 func (e *Executor) tasksWithDesc() (tasks []*taskfile.Task) {
 	tasks = make([]*taskfile.Task, 0, len(e.Taskfile.Tasks))
 	for _, task := range e.Taskfile.Tasks {