feat: create gui issue when assign require-ui label

[Yu-Jack]

These are examples for labeling backport and require-ui:

• Label one backport and one require-ui https://github.com/Yu-Jack/test/issues/155
  • One main issue
  • One backport issue from main issue
  • One GUI Issue
  • One backport issue from GUI issue
• Label two backports and one require-ui https://github.com/Yu-Jack/test/issues/144
  • One main issue
  • Two backports issues from main issue
  • One GUI issue
  • Two backports issues from GUI issue
• Label one require-ui https://github.com/Yu-Jack/test/issues/150
  • One GUI issue
  • If we just create GUI issue, we don't need to assign milestone for it.
  • Of course, we could create backport in GUI issue as well. https://github.com/Yu-Jack/test/issues/153

Currently, I will sync backport labels when I create the GUI issue cause. If we don't want that, I could remove that logic.

https://github.com/harvester/bot/issues/25

[Yu-Jack]

These two cases will result in two different output

• backport first, then require-ui later, it will create backport issue for GUI issue
• require-u first, then backport later, it won't create backport issue for GUI issue cause GUI issue doesn't have backport label when it's created at the moment.

And currently, it won't create GUI issue when labels contain area-ui. So, be careful that the issue which had created GUI issue before should have area-ui label to avoid duplicated GUI issue.