Ensure all examples from the GFM specification pass in client-side Markdown parser

The problem

In %15.1, we finished implementing support for deserializing for all the content types specified in the Commonmark and the GitHub Flavored Markdown specifications in the Content Editor.

However, after running the Snapshot tests that @cwoolley-gitlab has been working on in !89953 (merged), we noticed that there are 48 examples from the GitHub Flavored Markdown specification that the Content Editor can’t deserialize in the client.

The solution

We should ensure that the client-side parser provides robust support for Commonmark and GFM before moving forward with implementing support for GitLab Flavored Markdown. This is important because we can’t deliver a client-side parser that can’t process Markdown that is already supported by the backend.

Availability and Testing

Please ensure content_editor_spec E2E still passes for regression purposes. SET review of the MR would be beneficial.

Failing examples

Edited by Enrique Alcántara