[ci]: test each individual crate's manifest (#392)

* [ci]: test each crate outside workspace

We have bitten by these a few times now with that some features are leaked from the workspace
which makes it compile in the workspace but not using it's own Cargo.toml.

* [ci]: add tests for macos and windows

* add missed `WsServer` and `HttpServer`

* [ws server]: fix features

* debug failure in CI

* remove platform dependent assertion

* fix nit; proc-macros is proc-macros

* restore removed assertion

* remove whitespaces