Feature: Suggestion mode for comments

## Description

In lexical, there is a MarkNode that allows you to store the comment ID relative to the selected text fragment. This functionality can be extended to demonstrate, in the playground, a type of comment with suggested changes.

A comment in “suggest” mode must contain what is being replaced and with what. The comment text changes depending on the type of change: text change, format change, node change, deletion, addition

For example, how it looks in the Google Docs

Unlike regular comments, suggestions are easier to navigate one by one, so a separate pagination interface can be implemented for them. Here's what it looks like in Tiptap, for example.

This feature can be used to supplement the existing [agent-example](https://github.com/facebook/lexical/tree/main/examples/agent-example) shown on the home page https://lexical.dev. In particular, LLM can generate its own suggestion

## Impact

This popular feature in rich WYSIWYG editors will highlight the extensive capabilities of Lexical and facilitate integration

Start by reading the MarkNode comment-ID functionality and the playground, then inspect the existing agent-example integration. Define how suggestion comments represent text, format, node, deletion, and addition changes, and how they are navigated separately. Done means the playground demonstrates suggestion-mode comments with the requested change descriptions and pagination behavior.

Written by the indexing model from the issue text.