Show unlinked community PRs on the Open-tasks page

[TheCodedKid]

What

Follow-up to final comments in #396
Some community PRs don't map to any issue on the issue boards themselves. (Example #356)
It would be good to bring these contributions to the community's attention, so they can help review and discuss them.

Proposal

Extend tools/generate_open_tasks.py to also render a section of open PRs that:

• are not linked to an issue
• are authored by users who are not members of the flipperdevices org

Credit: idea from @NickVolynkin.

[TheCodedKid]

Gonna get to work on this later today, let me know what you all think.

[hedger]

The PR in question is closed, it's pure low effort AI slop and does not relate to Flipper One.

[TheCodedKid]

@hedger alright, I can close the PR. My apologies, I misunderstood the scope. Maybe got a bit excited to contribute.

Edit: After reading through the references, I see what you are saying. I appreciate the heads up, would you still like me to finish this feature? If so, I can re-open it. @NickVolynkin @hedger

[NickVolynkin]

@hedger yep, I linked that issue by mistake. This issue stays valid.

[TheCodedKid]

I finish this up