feat: add comment list APIs for theme-side

[guqing]

What type of PR is this?

/kind feature /milestone 2.0 /area core /kind api-change

What this PR does / why we need it:

• 新增主题端评论列表功能
• 新增 <halo:comment /> html tag 用于扩展评论组件
• 插件可以实现 CommentWidget 扩展点来渲染评论组件 html 块，以替换 <halo:comment /> 标签

Which issue(s) this PR fixes:

Fixes #2432

Special notes for your reviewer:

/cc @halo-dev/sig-halo

Does this PR introduce a user-facing change?

新增主题端评论列表功能

[ruibaby]

/retitle feat: add comment list APIs for theme-side

[ruibaby]

插件可以实现 CommentWidget 扩展点来渲染评论组件 html 块，以替换 <halo:comment /> 标签

@guqing 可以描述一下怎么在插件里面扩展 CommentWidget 这个拓展点吗？

[guqing]

插件可以实现 CommentWidget 扩展点来渲染评论组件 html 块，以替换 <halo:comment /> 标签

@guqing 可以描述一下怎么在插件里面扩展 CommentWidget 这个拓展点吗？

首先插件实现扩展点 CommentWidget

class DefaultCommentWidget implements CommentWidget {
    void render(...) {
        // 实现里面的逻辑，见下文
    }
} 

一种是使用 IModelFactory 构造 html 结构，类似 VNode，使用场景适合动态值拼接

IModelFactory modelFactory = context.getModelFactory();
IModel model = modelFactory.createModel();
model.add(modelFactory.createText("文字Node"));
IOpenElementTag p = modelFactory.createOpenElementTag("p");
modelFactory.setAttribute(p, "class", "text-center");
model.add(p);
model.add(modelFactory.createText(HtmlUtils.htmlEscape("p 标签中的文字")));
model.add(modelFactory.createCloseElementTag("p"));
// render 后 modelFactory 就会解析为：文字Node<p class="text-center">p 标签中的文字</p>
structureHandler.replaceWith(model, false);

一种是直接使用字符串

String text = """
<p>hello world</p>
""";
structureHandler.replaceWith(text, false);

[ruibaby]

@guqing 懂了（joke）

https://github.com/halo-sigs/plugin-comment-widget

PR Welcome 😃

[guqing]

/hold until #2443 merged

[f2c-ci-robot[bot]]

[APPROVALNOTIFIER] This PR is APPROVED

This pull-request has been approved by: JohnNiang

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[JohnNiang]

/unhold