Auto-populate description box when github button is toggled

[ecurrencyhodler]

When creating a bounty, sometimes a github link to an issue is provided. We should populate the description box with the information in the issue when the button gets toggled on.

Before we go to this page and if there is a github link, make a request to grab description. The toggle should be turned on my default on Step 3.

BLOCKERS:

• The backend must get updated to receive a separate call to get this data before the save button is hit.

Originally posted by @kevkevinpal in https://github.com/stakwork/sphinx-tribes/issues/1145#issuecomment-1863516693