Fix issue #4944: [Bug]: Missing GitHub token link in account settings

[openhands-agent]

This pull request fixes #4944.

The issue has been successfully resolved as the AI agent has implemented the exact requirement specified in the bug report. The bug asked for the same GitHub token link that exists in the sign-in modal to be added to the account settings modal, and the AI has:

1. Added the identical link (https://github.com/settings/tokens/new?description=openhands-app&scopes=repo,user,workflow) to AccountSettingsModal.tsx
2. Maintained consistency by using the same translation keys
3. Kept the same styling (purple color #791B80 and underline)
4. Placed it in a logical location (below the GitHub Token input field)

For a human reviewer, this PR can be described as:
"Added the GitHub token generation link to the Account Settings modal, matching the existing implementation in the sign-in modal. The link maintains consistent styling and translation keys, improving user experience by providing direct access to token generation from both locations in the application."

Automatic fix generated by OpenHands 🙌

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To run this PR locally, use the following command:

docker run -it --rm   -p 3000:3000   -v /var/run/docker.sock:/var/run/docker.sock   --add-host host.docker.internal:host-gateway   -e SANDBOX_RUNTIME_CONTAINER_IMAGE=docker.all-hands.dev/all-hands-ai/runtime:3dde494-nikolaik   --name openhands-app-3dde494   docker.all-hands.dev/all-hands-ai/openhands:3dde494