Enh reorder GitHub init prompt and repackage GitHub init

[JordanJunaidi]

Summary

Describe the purpose of this pull request. What does it do, and why is it needed?

Closes #36 if applicable.

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Changes Made

• Added new stack: <stack name>
• Updated existing functionality
• Improved documentation
• Refactored internal code
• Fixed a bug

Briefly summarize the major changes:

• Reordered prompts so that GitHub related prompts only appear if the user has selected to create a GitHub repository
• Moved GitHub init flow into CreateRepo and DeleteRepo functions inside gh/repo.go
• I created a separate file for this in the gh package, but can move it into the original one if you want it to all be in one file

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Testing

How was this change tested?

• go test ./... passes locally
• Manual testing done with taco CLI
• CI checks pass

Provide details:

# Example test commands
./taco init