allow urls in the /cherry-pick command

[kasperk81]

e.g. /cherry-pick https://github.com/llvm/llvm-project/commit/80f444646c62ccc8b2399d60ac91e62e6e576da6 on the ui looks legit:

/cherry-pick 80f4446

it was failing with a cryptic message:
Failed to cherry-pick: 80f4446

now it will allow us to do things like

/cherry-pick 123def https://github.com/llvm/llvm-project/321fed abcdef

and the script will cherry-pick 123def, 321fed and abcdef.

[github-actions]

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