feat: add a pending status for apply when running plan command

[AndreZiviani]

This PR adds the following improvements:

• add a pending apply status when a plan command is issued (including autoplan), this allows to configure the repository to only be mergeable if atlantis applied all changes
• fix apply logic that changed the PR status before checking if it is mergeable
• if only atlantis/apply status is pending/failing consider the PR mergeable

With these changes we can configure the GitHub repository to only be mergeable if: all status succeed, at least 1 approval from CODEOWNERS and only allow merging after atlantis is finished

Fix #1924, Fix #1791

[AndreZiviani]

I'm running with no problems for more than a month, can someone review please?

[AndreZiviani]

@chenrui333 could you please review this 🙏

[chenrui333]

lgtm, thanks!!

[chenrui333]

@AndreZiviani thanks for the work on this. 🙏 Gonna cut a new release today!

[rayterrill]

@AndreZiviani is there any configuration required to sue this new functionality? This sounds like exactly what we've been looking for - we want CODEOWNERS to be required before you can apply AND want to make atlantis/apply required.

[AndreZiviani]

Hey @rayterrill these are my branch protection rules, working perfectly so far

[zxpower]

This feature completely broke our workflow in Github Actions where we relied on https://github.com/WyriHaximus/github-action-wait-for-status to continue.

[jamengual]

@AndreZiviani I think this might have broken the status for all other VCS implementations:

look this please #2138

if we do not hear from you soon I will revert this change since is affecting quite a lot of people.

@chenrui333

[AndreZiviani]

@jamengual sorry my change broke other workflows :(
I’m not sure how to proceed, I could try adding a feature flag for this, what do you suggest?

[jamengual]

@AndreZiviani this is affecting github users as well so I think we need to revert it back then we can have a prerelease with this feature after you get feedback from people that this is working for them too, unless you can test in other VCSs by yourself.

[AndreZiviani]

I agree that a rollback is necessary, I will try to gather feedback and improve this on the following days