Enhance github plugin user flow to include forking repos

[pgoos]

For implement feature and create PR scenario, we should support the case where an agent (via github token) doesn't have access to push to the repo specified. In such case, the agent should:

• fork the repo
• checkout new branch locally (forked repo)
• implement changes and commit them
• push changes to the remote (forked repo)
• create a PR against original repo comparing a branch from forked repo
  That would allow us to support repos like elizaOS

[github-actions]

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