Add Codemod to Wrap @example Tag Content in a ts Fence for Consistent Rendering

[gcanti]

Currently, the @example tag content is not consistently wrapped in a ts fence, which causes rendering issues in some environments, such as in the popovers of Twoslash snippets on the website. While editors like VSCode handle unwrapped @example tags fine, other environments might not render them correctly. To solve this, I propose adding a codemod to ensure all @example tag content is wrapped in a ts fence.

Codemod Behaviour: For each @example tag, check if the content is already wrapped in a ts fence. If not, automatically wrap it in a ts fence.