Revert build-embed option as boolean

[crazywhalecc]

What does this PR do?

Revert build-embed option as boolean. Related: php/frankenphp#1651 (comment)

This should not be a bug, but this would be misleading. Although docopt requires options to support space reading, it will cause some confusion according to our habits, especially in other SAPIs --build-XXX does not accept values.

But I think it is acceptable to use another option to override the default environment variable (such as --with-embed-type=shared, if you still feel it is necessary to override it with the command.

Otherwise, we consider it a bad practice to encourage others to put all parameters after the extensions.

Checklist before merging

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• If you modified *.php or *.json, run them locally to ensure your changes are valid:
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  • composer analyse
  • composer test
  • bin/spc dev:sort-config
• If it's an extension or dependency update, please ensure the following:
  • Add your test combination to src/globals/test-extensions.php.
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[henderkes]

A --with-embed-type=static|shared option would be a good compromise. I'll go back to the drawing board to figure out a better alternative.