Add headers handler in CLI SAPI

[joanhey]

Check issue #12304

With this change, we can use the headers from CLI SAPI. But the most important think is that we can also use setcookie() and sessions.
And also it's useful for PHP tests from CLI.

All the included tests pass.

Only fail the actual header() and friends [ext/standard/tests/general_functions/head.phpt] that test the old behavior.
I can change this test if this PR will be accepted. But now this test show the difference. Changed.
https://github.com/joanhey/php-src/blob/cli-header-handler/ext/standard/tests/general_functions/head.phpt

BC: Nothing
That functions now do nothing from CLI.

I don't think that this feature need an RFC, but you'll say it.

Thank you

[joanhey]

✋ anybody could review it or start a discussion ??

PD: I can start it later in internals if necessary !!

[bukka]

So I think this needs an RFC because it changes the way how CLI treats header function. I can see your use case but as can be seen in the issue, there is already one objection to it (note about throwing exception instead) so that alone shows there should be probably RFC.

Also changing behaviour is in some way a BC break as you actually needed to change one of the standard test. This would be still acceptable for minor version IMO but it should not state there is no BC break at all.