feat: support custom inline renderer

[jajugoguma]

Please check if the PR fulfills these requirements

• It's the right issue type on the title
• When resolving a specific issue, it's referenced in the PR's title (e.g. fix #xxx[,#xxx], where "xxx" is the issue number)
• The commit message follows our guidelines
• Tests for the changes have been added (for bug fixes/features)
• Docs have been added/updated (for bug fixes/features)
• It does not introduce a breaking change or has a description of the breaking change

Description

• Added custom inline HTML renderer.
• Can use the custom inline function by giving the editor's customHTMLRenderer option as shown below.

const editor = new Editor({
  // ...
  customHTMLRenderer: {
    customInline(node, { entering, skipChildren, origin }) {
      const { info } = node;

      if (info === "katex" && entering) {
        skipChildren();

        const exp = node.literal || node.firstChild?.literal || "";
        const renderedKatex = katex.renderToString(exp, {
          throwOnError: false
        });

        return [
          { type: "openTag", tagName: "span", classNames: ["tui-katex"] },
          { type: "html", content: renderedKatex },
          { type: "closeTag", tagName: "span" }
        ];
      }
      return origin();
    },
    // ...
  }
});

As-Is

To-Be

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Thank you for your contribution to TOAST UI product. 🎉 😘 ✨

[jajugoguma]

두레이 래퍼에서 에디터 기능을 강제로 확장하면서 타입에러가 발생합니다. 이는 신경쓰지 않으셔도 됩니다!

[jwlee1108]

리뷰 완료합니다.

[lja1018]

리뷰 완료합니다.