Create or update screenshot comment

[takahirom]

Idea Description

Currently our screenshot test will post multiple times. But the screenshot comment will be long. So we would like to make it shot.
This can be the blocker of introducing this to production apps.

https://github.com/DroidKaigi/conference-app-2022/blob/main/.github/workflows/CommentPR.yml#L83

I think we can use this. But It is ok to rely on third party actions.

https://github.com/actions/github-script/blob/main/.github/workflows/pull-request-test.yml#L30

Reference images and links