Invert flow for start work on an issue to pick issue first

[justinrobots]

After initiating the "Start work from an issue" flow:

• Ask user to search for/select an issue first
• Then initiate the current branch creation flow:
  • this flow will end with a selection to "Create and switch to a branch" or "Create the branch on a new worktree"
  • don't show the option to create a branch without switching to it in this flow, since the intent is to start work now

Related to #3808 that removes the normal branch creation flow from the "Start work" button.

[axosoft-ramint]

Done in commit: cf00fc4

[github-actions]

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