feat: create GH issues for existing WIs in GUS

[mohanraj-r]

Sometimes we have existing WIs that need to create corresponding issues for and mirror the content. Would be great if we can specify a WI ID when creating an GH issue with a special tag/instruction e.g. to indicate to the bot that the contents of the GH issue can be overridden with the content of the specified WI.

[uip-robot-zz]

Git2Gus App is installed but the .git2gus/config.json doesn't exist.