[Feat] Add -update-condition option for github-coment exec

[ponkio-o]

Feature Overview

I want -update-condition option for exec subcommand.

Already implemented on github-comment post.
#473

Why is the feature needed?

I'm using github-comment exec to post the results of the tfmigrate plan with tfaction.
https://github.com/suzuki-shunsuke/tfaction/blob/cabe7eaf085f72969afb407ba0270e4e7219cfa2/tfmigrate-plan/main.sh#L39-L43

This feature is very useful. But, increase new comment when added commit. Therefore, I want to replace exists comment instead of to post new comment.

Does the feature include Breaking Changes?

No

Example Code

$ github-comment exec -update-condition 'Comment.HasMeta && Comment.Meta.TemplateKey == "foo"' -k foo

Reference

• Improve the comment of tfmigrate plan tfaction#899
• [Feat] Add an option to edit previous comment instead of posting a new one #473