Adds support for new help50

[dmalan]

TODO

• Implement _helped, _helpful, and _helpless once commands exist for help50 button.

Initially and temporarily, this version will also mention help50 button to students whenever a program exits with non-0 status, to introduce the new feature:

• Add help50 prompts to cs50.ai
• Add api/v1/help endpoint to cs50.ai
• Add commands help50.ask, help50.say, help50.showButton, help50.hideButton to help50.vsix.

[rongxin-liu]

Dependencies:
https://github.com/cs50/cs50.ai-config/pull/53
https://github.com/cs50/cs50.ai/pull/116
cs50/help50.vsix@173d9e1

[rongxin-liu]

In the codespace terminal, you can run update50 -t latest_help50 to test the help50 integration.

Here's why it would work:

The codespace image built for this branch (or any branch that is not main or develop is using cs50/cli:canary, which has the latest changes from the help50 branch in the cs50/cli repo.

Any new changes made to cs50/cli will be reflected on the cs50/cli:canary image.