[RFC]: Drop ext-openswoole with no replacement

[Xerkus]

Previously, we discussed splitting this package into two each declaring explicit dependency on either ext-swoole or ext-openswoole. A need for such split was dictated by the diverging API in those two extensions. See https://github.com/laminas/technical-steering-committee/blob/9e73fae14dd1bc8bdcdf875485353269af018de0/meetings/minutes/2023-05-08-TSC-Minutes.md

However, a year and a half passed since that TSC meeting. It is now apparent that openswoole does not have the kind of industry support and project activity required for such a fundamental extension.

At this point, I propose to drop the openswoole support entirely with no replacement. We will immediately remove it from documentation and from composer suggests.

At the same time we will begin a work on the new major release. Starting with a new major release this component will depend on a specific major versions of ext-swoole. This would allow us to utilize latest features in ext-swoole and to handle any BC breaking changes coming from the adoption of the current PHP features or from dependencies like #134