Issue Templates: add option to have dropdown printed list (#31577)

Issue Templates: add option to have dropdown printed list (#31577)

Issue template dropdown can have many entries, and it could be better to
have them rendered as list later on if multi-select is enabled.

so this adds an option to the issue template engine to do so.

DOCS: https://gitea.com/gitea/docs/pulls/19

---

## demo:

```yaml
name: Name
title: Title
about: About
labels: ["label1", "label2"]
ref: Ref
body:
  - type: dropdown
    id: id6
    attributes:
      label: Label of dropdown (list)
      description: Description of dropdown
      multiple: true
      list: true
      options:
        - Option 1 of dropdown
        - Option 2 of dropdown
        - Option 3 of dropdown
        - Option 4 of dropdown
        - Option 5 of dropdown
        - Option 6 of dropdown
        - Option 7 of dropdown
        - Option 8 of dropdown
        - Option 9 of dropdown
```

![image](https://github.com/user-attachments/assets/102ed0f4-89da-420b-ab2a-1788b59676f9)

![image](https://github.com/user-attachments/assets/a2bdb14e-43ff-4cc6-9bbe-20244830453c)

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