chore(actions): support cron schedule task (#26655)

Replace #22751 

1. only support the default branch in the repository setting.
2. autoload schedule data from the schedule table after starting the
service.
3. support specific syntax like `@yearly`, `@monthly`, `@weekly`,
`@daily`, `@hourly`

## How to use

See the [GitHub Actions
document](https://docs.github.com/en/actions/using-workflows/events-that-trigger-workflows#schedule)
for getting more detailed information.

```yaml
on:
  schedule:
    - cron: '30 5 * * 1,3'
    - cron: '30 5 * * 2,4'

jobs:
  test_schedule:
    runs-on: ubuntu-latest
    steps:
      - name: Not on Monday or Wednesday
        if: github.event.schedule != '30 5 * * 1,3'
        run: echo "This step will be skipped on Monday and Wednesday"
      - name: Every time
        run: echo "This step will always run"
```

Signed-off-by: Bo-Yi.Wu <appleboy.tw@gmail.com>

---------


Co-authored-by: Jason Song <i@wolfogre.com>
Co-authored-by: techknowlogick <techknowlogick@gitea.io>
Co-authored-by: wxiaoguang <wxiaoguang@gmail.com>
Co-authored-by: Lunny Xiao <xiaolunwen@gmail.com>

models/actions/schedule_spec.go

@@ -0,0 +1,50 @@
+// Copyright 2023 The Gitea Authors. All rights reserved.
+// SPDX-License-Identifier: MIT
+
+package actions
+
+import (
+	"context"
+
+	"code.gitea.io/gitea/models/db"
+	repo_model "code.gitea.io/gitea/models/repo"
+	"code.gitea.io/gitea/modules/timeutil"
+
+	"github.com/robfig/cron/v3"
+)
+
+// ActionScheduleSpec represents a schedule spec of a workflow file
+type ActionScheduleSpec struct {
+	ID         int64
+	RepoID     int64                  `xorm:"index"`
+	Repo       *repo_model.Repository `xorm:"-"`
+	ScheduleID int64                  `xorm:"index"`
+	Schedule   *ActionSchedule        `xorm:"-"`
+
+	// Next time the job will run, or the zero time if Cron has not been
+	// started or this entry's schedule is unsatisfiable
+	Next timeutil.TimeStamp `xorm:"index"`
+	// Prev is the last time this job was run, or the zero time if never.
+	Prev timeutil.TimeStamp
+	Spec string
+
+	Created timeutil.TimeStamp `xorm:"created"`
+	Updated timeutil.TimeStamp `xorm:"updated"`
+}
+
+func (s *ActionScheduleSpec) Parse() (cron.Schedule, error) {
+	return cronParser.Parse(s.Spec)
+}
+
+func init() {
+	db.RegisterModel(new(ActionScheduleSpec))
+}
+
+func UpdateScheduleSpec(ctx context.Context, spec *ActionScheduleSpec, cols ...string) error {
+	sess := db.GetEngine(ctx).ID(spec.ID)
+	if len(cols) > 0 {
+		sess.Cols(cols...)
+	}
+	_, err := sess.Update(spec)
+	return err
+}