Loading state for "Checkout Source Branch" button

[mkenchugonde]

The 'Checkout source Branch' button in the Pull Request view doesn't have a loading state and this PR will add this feature. This will help that the checkout is in progress instead of clicking the button multiple times

[atlassian-cla-bot]

Thank you for your submission! Like many open source projects, we ask that you sign our CLA (Contributor License Agreement) before we can accept your contribution.
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❌mkenchugonde

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[sdzh-atlassian]

Hi @mkenchugonde! Thanks for the PR :)

I'm assuming you're a colleague; not sure why it's complaining about the CLA issue - but it's most likely because you're not part of atlassian github org 🤔

IIRC there's a self-serve way of linking your account outlined in Confluence - but if that doesn't help, please feel free to hit me up on Slack, or raise it with #opensource

[sdzh-atlassian]

Looks good to me! ;)