Command to early-exit the job and set check conclusion

Describe the enhancement
Currently to skip the rest of steps during a job, an if condition has to be added to all of steps or steps have to be moved to another job.

It'd be nice to have a command to early-exit (premature, prematurely, graceful, gracefully) (end, finish, terminate, termination, stop, halt, skip, cancel, discontinue, fail) the job during a step without failing the job:

::exit::

It'd be also nice to set the conclusion of early-exited job:

::exit::failure

(equivalent to exit 1)
or

::exit::neutral

(equivalent to exit 78 in Actions v1)
and other check conclusions.

This would help save build time for both GitHub and customers.

Additional information

Related StackOverflow and GitHub Community posts:

• How to fail a job in Github Actions?
• How to force to exit in Github Actions step
• How to write a GitHub Action with a neutral Check Run status
• How to perform an early clean exit of a job ?
• Early successful termination of job
• Github Action Skip Steps/Fall Through Syntax

Related issues:

• https://github.com/actions/toolkit/issues/146
• https://github.com/veggiemonk/skip-commit

Other CIs:

• CircleCI: circleci-agent step halt
• Travis CI: travis_terminate
• AppVeyor: appveyor exit (Linux)
• Jenkins: currentBuild.result
• GitLab CI: exit 0

No files, tests, or entry points are named in the issue. Start by reviewing the requested command syntax, the linked toolkit issue, and the Checks API conclusion values; done means a job can stop from a step without failing and can report the requested conclusion.