Support deleting edit-history revisions for issue and PR descriptions

首先检查公开的 GraphQL API 是否支持文档中所述的 UserContentEdit 数据和删除 mutation，并查找 issue 中提到的前置 API 跟踪请求。比较现有的 gh issue edit、gh pr edit 和 gh api graphql 工作流。完成的标准是：受支持的 CLI 命令可以列出并选择修订版本，要求进行可识别的确认，删除所选内容，并保留编辑者和时间戳元数据。

Describe the feature or problem you’d like to solve

GitHub’s web UI lets authors remove a previous revision’s content through edited → Options → Delete revision from history.

gh issue edit and gh pr edit update the current description, but there is no equivalent command to remove a superseded revision’s content. Completing that workflow requires switching to the browser.

This capability would also be useful for comments, particularly when an earlier version contains sensitive information.

Proposed solution

Support listing edit-history revisions and deleting a selected revision’s content using normal GitHub CLI authentication.

Deletion should require confirmation identifying the issue, PR, or comment and the selected revision. It should preserve the editor and timestamp metadata, matching the website’s behavior.

This would let users complete the workflow from the CLI without handling browser-session credentials.

Additional context

GitHub documents the existing browser operation in Tracking changes in a comment.

The public GraphQL API exposes UserContentEdit, including id, diff, deletedAt, and deletedBy. However, a public API request using deleteUserContentEdit was rejected with:

DeleteUserContentEditInput isn't a defined input type
Field 'deleteUserContentEdit' doesn't exist on type 'Mutation'

A successful deletion through the website used a request containing:

{
  "persistedQueryName": "deleteUserContentEditMutation",
  "variables": {
    "input": {
      "id": "<revision ID>"
    }
  }
}

This appears to be an internal website operation rather than a mutation available through gh api graphql. The requested CLI functionality should use a supported API rather than depend on the website’s private endpoint.

If a public API addition is required first, please identify or link the prerequisite tracking request.