Add role for the framework team!

[Piinks]

Adds job listing to the website for the open framework role!

Presubmit checklist

• If you are unwilling, or unable, to sign the CLA, even for a tiny, one-word PR, please file an issue instead of a PR.
• If this PR is not meant to land until a future stable release, mark it as draft with an explanation.
• This PR follows the Google Developer Documentation Style Guidelines—for example, it doesn't use i.e. or e.g., and it avoids I and we (first-person pronouns).
• This PR uses semantic line breaks
  of 80 characters or fewer.

[gemini-code-assist]

Code Review

This pull request adds a new job listing for a Senior Software Engineer on the Flutter Framework team. The changes include adding a link to the main jobs page and creating a new markdown file for the job description. My review focuses on ensuring the new content adheres to the project's documentation style guides, as mentioned in the PR description. I've pointed out a few areas for improvement regarding semantic line breaks and wording to align with those guidelines.

[flutter-website-bot]

Visit the preview URL for this PR (updated for commit c3eb1c4):

https://flutter-docs-prod--pr13171-frameworkrole-bej3eqpp.web.app

[Piinks]

It looks like the failures are at head, not from this PR?

[Piinks]

Shweet! Thanks @parlough!

[parlough]

🥳 Thanks!